General Definition, Epidemiology and Neurobiological Bases of Learning Disabilities

**3**

**Chapter 1**

**Abstract**

*Maria Tzouriadou*

intervention RTI PSW

**1. Introduction**

Concepts and Ambiguities in the

Scholars and researchers have constantly argued due to the ambiguity and a lack of

consensus in the scientific community in defining what constitutes a learning disability. The difficulty in identifying a universal term is reflected in the multiple terms that are used interchangeably (e.g. learning disabilities, specific learning disabilities, dyslexia, minimal brain dysfunction). Most commonly accepted and used definitions (e.g. IDEIA) can be considered ambiguous as it excludes certain conditions and describes characteristics in terms of abilities, processes, and achievement without discrimination between these terms. The only constant criterion (across definitions) is the discrepancy criterion that is the discrepancy between ability and achievement. In this context, it is important to note the differences in conceptualizing ability and academic achievement. Currently, the scientific community appears to agree that (a) learning disabilities are a distinct disability manifesting in students with low academic achievement, (b) it is a developmental disability that impacts individuals across their lifetime, and (c) it is a product of the interaction between genetic and environmental contributing factors, with environmental factors being determining by sociocultural conditions. Interventions addressing learning disabilities are not always evidencebased; interventions can be influenced by socioeconomic circumstances and policy decisions. Consequently, it is necessary to approach learning disabilities with a holistic

and system-based approach rather than try to differentially diagnose them.

**Keywords:** learning disabilities, dyslexia, discrepancy criterion, evidence-based

Over the past years, learning disabilities (LD) or specific learning disabilities (SLD) have emerged as the most studied upon and renowned classification of special education with the term becoming synonymous with special education itself due to how frequently students are placed under this category. Nonetheless, it is also the special education category which has brought the most disagreement between scholars, researchers, and educators to this day, given that LD have not been established as a distinct discipline; that is, until now no causal relationship has been determined between the phenomenology of LD and the factors which cause them. Despite formal definitions, a lack of understanding of their nature and their interpretation exists, which indicates that the main goal of a distinct discipline is not fulfilled [1]. Without the understanding of their nature and interpretation, scientific standpoints regarding learning disabilities remain "into question" or "unfounded", and this constitutes the very root of the "identification problem" that

Field of Learning Disabilities

#### **Chapter 1**

## Concepts and Ambiguities in the Field of Learning Disabilities

*Maria Tzouriadou*

#### **Abstract**

Scholars and researchers have constantly argued due to the ambiguity and a lack of consensus in the scientific community in defining what constitutes a learning disability. The difficulty in identifying a universal term is reflected in the multiple terms that are used interchangeably (e.g. learning disabilities, specific learning disabilities, dyslexia, minimal brain dysfunction). Most commonly accepted and used definitions (e.g. IDEIA) can be considered ambiguous as it excludes certain conditions and describes characteristics in terms of abilities, processes, and achievement without discrimination between these terms. The only constant criterion (across definitions) is the discrepancy criterion that is the discrepancy between ability and achievement. In this context, it is important to note the differences in conceptualizing ability and academic achievement. Currently, the scientific community appears to agree that (a) learning disabilities are a distinct disability manifesting in students with low academic achievement, (b) it is a developmental disability that impacts individuals across their lifetime, and (c) it is a product of the interaction between genetic and environmental contributing factors, with environmental factors being determining by sociocultural conditions. Interventions addressing learning disabilities are not always evidencebased; interventions can be influenced by socioeconomic circumstances and policy decisions. Consequently, it is necessary to approach learning disabilities with a holistic and system-based approach rather than try to differentially diagnose them.

**Keywords:** learning disabilities, dyslexia, discrepancy criterion, evidence-based intervention RTI PSW

#### **1. Introduction**

Over the past years, learning disabilities (LD) or specific learning disabilities (SLD) have emerged as the most studied upon and renowned classification of special education with the term becoming synonymous with special education itself due to how frequently students are placed under this category. Nonetheless, it is also the special education category which has brought the most disagreement between scholars, researchers, and educators to this day, given that LD have not been established as a distinct discipline; that is, until now no causal relationship has been determined between the phenomenology of LD and the factors which cause them. Despite formal definitions, a lack of understanding of their nature and their interpretation exists, which indicates that the main goal of a distinct discipline is not fulfilled [1]. Without the understanding of their nature and interpretation, scientific standpoints regarding learning disabilities remain "into question" or "unfounded", and this constitutes the very root of the "identification problem" that

is the lack of consensus on how to better define a classification category for LD [2]. Over a course of more than 100 years of studies, we have been unable to provide a unanimous and conclusive answer to a simple question: What are learning disabilities? Today, we believe that we know a lot about their characteristics and the implemented practices, but we have not yet answered the question whether they represent a distinct category of students with low academic achievement or they are a construct into which all low-performing students can be classified under. These two aspects have been meticulously studied over time, albeit not cohesively; consequently, even today some claim that LD represent a specific difficulty, since these children have high intelligence, while others believe that this category includes every child who is unable to learn. Since the beginning of the twenty-first century, scientists from various disciplines, but mostly educators, often come across parents' questions such as "My child, who goes to kindergarten, writes backwards, is this dyslexia?", "Will my child be a future Einstein?", "My child has trouble understanding meanings. Could this be dyslexia?", or "My child is distrait and performs poorly at school. Could he or she be having learning disabilities?" These scientists have attempted, through international organizations, such as the Learning Disabilities Association (LDA), to functionally operationalize the field—that is, to answer whether it is a scientific discipline with particular characteristics or a "pseudoscience", which covers all and nothing—and they have tried to identify the operational characteristics that would help children reach their full potential within the context of school and society.

#### **2. Epistemological ambiguities of the field**

Up until the 1960s, education had shown no interest in learning disabilities. Nevertheless, legislated compulsory education, the study of the school drop-out phenomenon, and the development of school's knowledge-based character have led to the creation of a new classification category, none other than LD. The fact that school success was associated with an individual's subsequent social and professional success contributed also to the creation of this distinct category given that LD pertained to individuals who had the potential of success due to their attributed higher cognitive skills. Over the course of time, this perception has consolidated, and learning disabilities have become the most important category of special education. An important indicator of this is the following: programs for children with LD congregate the highest number of students with special educational needs. 2.5 million of American school students approximately 5% from the total public school enrolment identified with learning disabilities in 2009. These students represented 42% of the 5.9 million school-age children. This percentage varies across states [3]. For example, in Kentucky, 3.18% of students belong in the specific learning disabilities category, while in Massachusetts and Port Island, the corresponding figures are 9% and 9.6% [3]. Similar differentiations are currently observed both in Canada and in certain European countries [4]. The variety of prevalence reflects various factors, like the diversity of the population belonging in this category; the increasing school pressure for higher achievement, which has led to higher standards; the different criteria used for the assessment of achievement; as well as the criteria applied to delineate the field of learning disabilities. The presence of such determining factors has resulted in LD student rates to fluctuate among US states. Consequently, LD represents the largest field within special education.

Across time, various definitions have been formulated, attempting to demonstrate the field's key characteristics. However, each one of them has been vague, figurative, negative instead of affirmative, and tautological or excessively broad

**5**

terms dyslexia or learning disabilities [4].

*Concepts and Ambiguities in the Field of Learning Disabilities*

or restrictive. Each subsequent definition attempted to correct the preceding ones. Therefore, their analysis is imperative, not with the objective of formulating a new definition but to broaden the description and notably the understanding of what

The term learning disabilities was coined by Kirk, who also devised their first definition [5]. This definition introduced for the first time the concept of disorders in the psychological processes involved in academic learning. Nevertheless, ambiguities in the field's delineation can still be found in this definition. For example, it mentions that disabilities refer to *retardation*, *disorder*, *or delay* but does not proceed to determine any difference between these terms. The definition also introduces the element of exclusion from other conditions of deficit, suggesting the case of differential diagnosis. Exclusion, however, is not a criterion for specifying the characteristics that differentiate LD from other conditions. Despite its ambiguities, Kirk's definition marked the establishment of the new field of LD and became the

The acknowledgement of LD as an independent scientific field demanded the adoption of an operational definition, which would delineate its scope as a distinct category of special education. Such a definition was suggested by the US National Advisory Committee of Handicapped Children in 1968 [6]; it formed the basis for educational policies regarding children with LD and was included in the Individuals with Disabilities Education Act (IDEA) in 1997 [7]. Respectively, research in Europe and mainly in Britain focused on specific reading difficulties—dyslexia—and, even since the 1960s, there was the development of associations and treatment centers for children with this disorder [8, 9]. An important figure in the study of dyslexia in Britain was Critchley, who devised a definition for developmental dyslexia; according to his definition, it is a learning disorder which is initially manifested with difficulties in reading and later with "odd" spelling and difficulties in the use of written language. It is of cognitive nature and genetically determined. It is not caused by intellectual disability or lack of social and cultural chances, wrong instruction techniques, or emotional factors. Moreover, it is not due to any obvious structural cerebral insufficiency. Finally, Critchley did not agree with the use of the term "learning difficulties", because he believed that the children's only difficulty had to do with language [10]. Miles had another important scientific contribution in the study of dyslexia in Britain by conducting a large diachronic study during 1970–1980 on 14,000 children. According to the findings of this study, 3% of students showed severe symptoms of dyslexia and 6% mild symptoms. Miles also accepted that it was a hereditary disorder [11]. Rutter and his colleagues carried out epidemiological studies on children with reading difficulties and through them exhaustively highlighted specific reading difficulties. He argued that the terms and identification process used for dyslexia were chaotic and confusing, which is caused by the inability to interpret the nature of learning problems and may be confused with general reading retardation [12, 13]. In 1978, the British Department of Education and Science commissioned a committee to introduce a special education law in Britain, Wales, and Scotland in the spirit of normalisation and integration, a study that resulted in the Warnock Report (1978) which was adopted and became a law in 1983 [14]. In this law, it seems that an approach of low performance has been adopted under the term special educational needs regarding LD, with more than 18% of the student population being represented under this category. In this case dyslexia was not included as a category in special education, despite it being recognized as one. This is due to the fact that Britain adopted a purely pedagogical model at the administrative and practical level to address any educational needs of children. Most European countries have adopted Kirk's LD definition using the

*DOI: http://dx.doi.org/10.5772/intechopen.90777*

basis for every formal definition in the USA.

learning disabilities actually are.

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

is the lack of consensus on how to better define a classification category for LD [2]. Over a course of more than 100 years of studies, we have been unable to provide a unanimous and conclusive answer to a simple question: What are learning disabilities? Today, we believe that we know a lot about their characteristics and the implemented practices, but we have not yet answered the question whether they represent a distinct category of students with low academic achievement or they are a construct into which all low-performing students can be classified under. These two aspects have been meticulously studied over time, albeit not cohesively; consequently, even today some claim that LD represent a specific difficulty, since these children have high intelligence, while others believe that this category includes every child who is unable to learn. Since the beginning of the twenty-first century, scientists from various disciplines, but mostly educators, often come across parents' questions such as "My child, who goes to kindergarten, writes backwards, is this dyslexia?", "Will my child be a future Einstein?", "My child has trouble understanding meanings. Could this be dyslexia?", or "My child is distrait and performs poorly at school. Could he or she be having learning disabilities?" These scientists have attempted, through international organizations, such as the Learning Disabilities Association (LDA), to functionally operationalize the field—that is, to answer whether it is a scientific discipline with particular characteristics or a "pseudoscience", which covers all and nothing—and they have tried to identify the operational characteristics that would help children reach their full potential within the context

Up until the 1960s, education had shown no interest in learning disabilities. Nevertheless, legislated compulsory education, the study of the school drop-out phenomenon, and the development of school's knowledge-based character have led to the creation of a new classification category, none other than LD. The fact that school success was associated with an individual's subsequent social and professional success contributed also to the creation of this distinct category given that LD pertained to individuals who had the potential of success due to their attributed higher cognitive skills. Over the course of time, this perception has consolidated, and learning disabilities have become the most important category of special education. An important indicator of this is the following: programs for children with LD congregate the highest number of students with special educational needs. 2.5 million of American school students approximately 5% from the total public school enrolment identified with learning disabilities in 2009. These students represented 42% of the 5.9 million school-age children. This percentage varies across states [3]. For example, in Kentucky, 3.18% of students belong in the specific learning disabilities category, while in Massachusetts and Port Island, the corresponding figures are 9% and 9.6% [3]. Similar differentiations are currently observed both in Canada and in certain European countries [4]. The variety of prevalence reflects various factors, like the diversity of the population belonging in this category; the increasing school pressure for higher achievement, which has led to higher standards; the different criteria used for the assessment of achievement; as well as the criteria applied to delineate the field of learning disabilities. The presence of such determining factors has resulted in LD student rates to fluctuate among US states.

Consequently, LD represents the largest field within special education.

Across time, various definitions have been formulated, attempting to demonstrate the field's key characteristics. However, each one of them has been vague, figurative, negative instead of affirmative, and tautological or excessively broad

**4**

of school and society.

**2. Epistemological ambiguities of the field**

or restrictive. Each subsequent definition attempted to correct the preceding ones. Therefore, their analysis is imperative, not with the objective of formulating a new definition but to broaden the description and notably the understanding of what learning disabilities actually are.

The term learning disabilities was coined by Kirk, who also devised their first definition [5]. This definition introduced for the first time the concept of disorders in the psychological processes involved in academic learning. Nevertheless, ambiguities in the field's delineation can still be found in this definition. For example, it mentions that disabilities refer to *retardation*, *disorder*, *or delay* but does not proceed to determine any difference between these terms. The definition also introduces the element of exclusion from other conditions of deficit, suggesting the case of differential diagnosis. Exclusion, however, is not a criterion for specifying the characteristics that differentiate LD from other conditions. Despite its ambiguities, Kirk's definition marked the establishment of the new field of LD and became the basis for every formal definition in the USA.

The acknowledgement of LD as an independent scientific field demanded the adoption of an operational definition, which would delineate its scope as a distinct category of special education. Such a definition was suggested by the US National Advisory Committee of Handicapped Children in 1968 [6]; it formed the basis for educational policies regarding children with LD and was included in the Individuals with Disabilities Education Act (IDEA) in 1997 [7]. Respectively, research in Europe and mainly in Britain focused on specific reading difficulties—dyslexia—and, even since the 1960s, there was the development of associations and treatment centers for children with this disorder [8, 9]. An important figure in the study of dyslexia in Britain was Critchley, who devised a definition for developmental dyslexia; according to his definition, it is a learning disorder which is initially manifested with difficulties in reading and later with "odd" spelling and difficulties in the use of written language. It is of cognitive nature and genetically determined. It is not caused by intellectual disability or lack of social and cultural chances, wrong instruction techniques, or emotional factors. Moreover, it is not due to any obvious structural cerebral insufficiency. Finally, Critchley did not agree with the use of the term "learning difficulties", because he believed that the children's only difficulty had to do with language [10]. Miles had another important scientific contribution in the study of dyslexia in Britain by conducting a large diachronic study during 1970–1980 on 14,000 children. According to the findings of this study, 3% of students showed severe symptoms of dyslexia and 6% mild symptoms. Miles also accepted that it was a hereditary disorder [11]. Rutter and his colleagues carried out epidemiological studies on children with reading difficulties and through them exhaustively highlighted specific reading difficulties. He argued that the terms and identification process used for dyslexia were chaotic and confusing, which is caused by the inability to interpret the nature of learning problems and may be confused with general reading retardation [12, 13]. In 1978, the British Department of Education and Science commissioned a committee to introduce a special education law in Britain, Wales, and Scotland in the spirit of normalisation and integration, a study that resulted in the Warnock Report (1978) which was adopted and became a law in 1983 [14]. In this law, it seems that an approach of low performance has been adopted under the term special educational needs regarding LD, with more than 18% of the student population being represented under this category. In this case dyslexia was not included as a category in special education, despite it being recognized as one. This is due to the fact that Britain adopted a purely pedagogical model at the administrative and practical level to address any educational needs of children. Most European countries have adopted Kirk's LD definition using the terms dyslexia or learning disabilities [4].

In the USA, on the other hand, studies on better understanding the nature of LD and determining best practices in their identification continued. In 1989, the National Joint Committee on Learning Disabilities, based on new evidence and scientific findings, attempted to eradicate inherent ambiguities in the identification of the field, by formulating the following definition:

Learning disabilities is a general term that refers to a heterogeneous group of disorders manifested by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning, or mathematical abilities. These disorders are intrinsic to the individual, presumed to be due to central nervous system dysfunction, and may occur across the life span. Problems in self-regulatory behaviors, social perception, and social interaction may exist with learning disabilities but do not by themselves constitute a learning disability. Although learning disabilities may occur concomitantly with other disabilities (e.g. sensory impairment, intellectual disabilities, emotional disturbance) or with extrinsic influences (such as cultural or linguistic differences, insufficient or inappropriate instruction), they are not the result of those conditions or influences [15]*.* Regarding this definition, Kavale et al. [16] highlights that the term "in general" is vague, much like the term "specific" in the IDEA's definition, thus allowing various interpretations.

In 2004, the IDEA regulation maintained the same definition of SLD as previous versions of the law and regulations. Notably, an attempt to expand the identification process occurred by including both a process based on the child's response to scientific, research-based intervention, such as response to intervention (RTI), and the use of other alternative research-based procedures, such as the Patterns of Strengths and Weakness (PSW) model. The IDEA definition, found in US Code (20 U.S.C. & 1401 [17]), reads as follows:

*"The term 'specific learning disability' means a disorder in one or more of the basic psychological processes involved in understanding or in using language, spoken or written, which disorder may manifest itself in the imperfect ability to listen, think, speak, read, write, spell, or do mathematical calculations.*

*Such term includes such conditions as perceptual disabilities, brain injury, minimal brain dysfunction, dyslexia, and developmental aphasia.*

*Such term does not include a learning problem that is primarily the result of visual, hearing, or motor disabilities, of mental retardation, of emotional disturbance, or of environmental, cultural, or economic disadvantage" [18].*

This official definition introduces the "specific" aspect of the disorder for the first time, through the ambiguous distinction "in one or more", without specifying how many problems there could be in order for the disorder to be considered specific. Moreover, it provides no clarification of what specific means, if, for example, it refers to particular traits in the relevant subjects and the psychological structure or whether the term "specific" suggests that the disorder is idiopathic [19] that is of unknown cause. This definition also seems to introduce a hierarchy of processes, with language being dominant, whether oral or written. Furthermore, the disorder is not connected with difficulties in academic achievement alone but also with cognitive deficits (reasoning disorders), a trait that reflects what we nowadays call "metacognitive function". No mention of central nervous system dysfunctions appears yet, but there are references to similar cases deriving from neurological disorders.

Based on this legislation, educators are asked to identify if student suspected of SLD fails to show sufficient progress in achievement according to age-based

**7**

*Concepts and Ambiguities in the Field of Learning Disabilities*

• Reading fluency, including oral reading skills

• Reading comprehension strategies

criterion as part of the diagnostic procedure.

understanding of the condition.

and grade-level standards. This procedure provides important information and highlights a model of strengths and weaknesses in achievement and aptitudes. Intraindividual differences or variability are sometimes cited as an indication of SLD. The ability-achievement discrepancy is also taken into account as part of the process. It is also argued that qualified staff should provide appropriate instruction. Students who have not received it cannot be considered as having SLD. Key instruction elements mainly regard reading, which, according to age, should be taught

\*Source: National Institute of Child Health and Human Development

Schools also need to make frequent assessments of students' progress and inform parents. The gathered data might show the effectiveness of an instruction strategy or program. If the student does not exhibit any signs of progress, an extension may be granted—with the consent of the parents—which may not exceed 60 days.

Finally, the reauthorization regulations (NCLB) [21] included the statement that it is necessary to apply approaches to the instruction of reading that are supported by scientifically based reading research, mainly based on social construction. Concerning the instruction of reading, it has been argued that it may also be due to the over-representation of minorities in special education [22]. The reauthorized definition allowed US states to not use the IQ-achievement discrepancy or not provide intelligence tests as part of the diagnostic procedure and to include the RTI

The DSM uses the term "specific learning disorder". Revised in 2013, the current version, DSM-5, broadens the previous definition to reflect the latest scientific

The diagnosis requires persistent difficulties in reading, writing, arithmetic, or mathematical reasoning skills during formal years of schooling. Symptoms may include inaccurate or slow and effortful reading, poor written expression that lacks clarity, difficulties remembering number facts, or inaccurate mathematical reasoning. Current academic skills must be well below the average range of scores in culturally and linguistically appropriate tests of reading, writing, or mathematics. The individual's difficulties must not be better explained by developmental, neurological, sensory (vision or hearing), or motor disorders and must significantly interfere with academic achievement, occupational performance, or activities of daily living. Specific learning disorder is diagnosed through a clinical review of the individual's developmental, medical, educational, and family history, reports of test scores and teacher observations, and response to academic interventions [23]. There was intense research on an international level—but mostly in the USA—and millions of dollars were spent in the pursuit of the field's delineation [24]. However, as of yet there is no crystallized description of the condition but rather a generalized depiction of a group of school children with difficulties in learning. We may know a lot about the condition, but we do not know why LD exist.

*DOI: http://dx.doi.org/10.5772/intechopen.90777*

systematically:

• Phonics

(NICHD) [20].

• Phonemic awareness

• Vocabulary development

#### *Concepts and Ambiguities in the Field of Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.90777*

and grade-level standards. This procedure provides important information and highlights a model of strengths and weaknesses in achievement and aptitudes. Intraindividual differences or variability are sometimes cited as an indication of SLD. The ability-achievement discrepancy is also taken into account as part of the process.

It is also argued that qualified staff should provide appropriate instruction. Students who have not received it cannot be considered as having SLD. Key instruction elements mainly regard reading, which, according to age, should be taught systematically:


*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

"specific" in the IDEA's definition, thus allowing various interpretations.

*speak, read, write, spell, or do mathematical calculations.*

*brain dysfunction, dyslexia, and developmental aphasia.*

*of environmental, cultural, or economic disadvantage" [18].*

of the field, by formulating the following definition:

U.S.C. & 1401 [17]), reads as follows:

In the USA, on the other hand, studies on better understanding the nature of LD and determining best practices in their identification continued. In 1989, the National Joint Committee on Learning Disabilities, based on new evidence and scientific findings, attempted to eradicate inherent ambiguities in the identification

Learning disabilities is a general term that refers to a heterogeneous group of disorders manifested by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning, or mathematical abilities. These disorders are intrinsic to the individual, presumed to be due to central nervous system dysfunction, and may occur across the life span. Problems in self-regulatory behaviors, social perception, and social interaction may exist with learning disabilities but do not by themselves constitute a learning disability. Although learning disabilities may occur concomitantly with other disabilities (e.g. sensory impairment, intellectual disabilities, emotional disturbance) or with extrinsic influences (such as cultural or linguistic differences, insufficient or inappropriate instruction), they are not the result of those conditions or influences [15]*.* Regarding this definition, Kavale et al. [16] highlights that the term "in general" is vague, much like the term

In 2004, the IDEA regulation maintained the same definition of SLD as previous versions of the law and regulations. Notably, an attempt to expand the identification process occurred by including both a process based on the child's response to scientific, research-based intervention, such as response to intervention (RTI), and the use of other alternative research-based procedures, such as the Patterns of Strengths and Weakness (PSW) model. The IDEA definition, found in US Code (20

*"The term 'specific learning disability' means a disorder in one or more of the basic psychological processes involved in understanding or in using language, spoken or written, which disorder may manifest itself in the imperfect ability to listen, think,* 

*Such term includes such conditions as perceptual disabilities, brain injury, minimal* 

*Such term does not include a learning problem that is primarily the result of visual, hearing, or motor disabilities, of mental retardation, of emotional disturbance, or* 

This official definition introduces the "specific" aspect of the disorder for the first time, through the ambiguous distinction "in one or more", without specifying how many problems there could be in order for the disorder to be considered specific. Moreover, it provides no clarification of what specific means, if, for example, it refers to particular traits in the relevant subjects and the psychological structure or whether the term "specific" suggests that the disorder is idiopathic [19] that is of unknown cause. This definition also seems to introduce a hierarchy of processes, with language being dominant, whether oral or written. Furthermore, the disorder is not connected with difficulties in academic achievement alone but also with cognitive deficits (reasoning disorders), a trait that reflects what we nowadays call "metacognitive function". No mention of central nervous system dysfunctions appears yet, but there are references to similar cases deriving from

Based on this legislation, educators are asked to identify if student suspected of SLD fails to show sufficient progress in achievement according to age-based

**6**

neurological disorders.


\*Source: National Institute of Child Health and Human Development (NICHD) [20].

Schools also need to make frequent assessments of students' progress and inform parents. The gathered data might show the effectiveness of an instruction strategy or program. If the student does not exhibit any signs of progress, an extension may be granted—with the consent of the parents—which may not exceed 60 days.

Finally, the reauthorization regulations (NCLB) [21] included the statement that it is necessary to apply approaches to the instruction of reading that are supported by scientifically based reading research, mainly based on social construction. Concerning the instruction of reading, it has been argued that it may also be due to the over-representation of minorities in special education [22]. The reauthorized definition allowed US states to not use the IQ-achievement discrepancy or not provide intelligence tests as part of the diagnostic procedure and to include the RTI criterion as part of the diagnostic procedure.

The DSM uses the term "specific learning disorder". Revised in 2013, the current version, DSM-5, broadens the previous definition to reflect the latest scientific understanding of the condition.

The diagnosis requires persistent difficulties in reading, writing, arithmetic, or mathematical reasoning skills during formal years of schooling. Symptoms may include inaccurate or slow and effortful reading, poor written expression that lacks clarity, difficulties remembering number facts, or inaccurate mathematical reasoning. Current academic skills must be well below the average range of scores in culturally and linguistically appropriate tests of reading, writing, or mathematics. The individual's difficulties must not be better explained by developmental, neurological, sensory (vision or hearing), or motor disorders and must significantly interfere with academic achievement, occupational performance, or activities of daily living. Specific learning disorder is diagnosed through a clinical review of the individual's developmental, medical, educational, and family history, reports of test scores and teacher observations, and response to academic interventions [23].

There was intense research on an international level—but mostly in the USA—and millions of dollars were spent in the pursuit of the field's delineation [24]. However, as of yet there is no crystallized description of the condition but rather a generalized depiction of a group of school children with difficulties in learning. We may know a lot about the condition, but we do not know why LD exist. Even the definitions' points of convergence do not lead to a uniform interpretation of their nature. For this reason, in numerous studies and research, SLD are approached from different perspectives, and different terms are used to describe them, such as learning disabilities, specific learning disabilities, dyslexia, specific language impairment, attention deficit hyperactivity disorder, etc. But in all formal definitions, the element of ability-achievement discrepancy appears constantly.

The problem of discrepancy raises a reasonable question: "What is the meaning of concepts such as intelligence or general cognitive ability, learning or cognitive processes, and academic achievement—concepts that are included in every definition of SLD—and what is the causal relationship between them?" [4]. Unless this question is resolved, the identification of the field will remain vague and contentious. Since conceptual and scientific definitions did not facilitate the identification of the SLD field, an operational description of the condition was required for practical implementation. The phenomenon of intra-individual differences was first studied, particularly the possibility of some "malfunctioning" of certain abilities in contrast to the normal development of others. These developmental imbalances could become apparent in discrepancies of intelligence functions, which are included in intelligence testing, such as the Wechsler Intelligence Scale for Children (WISC). WISC composites can be used to identify profiles of strengths and weaknesses, which can distinguish students with SLD from other groups of students with average or low overall intelligence function scores. This analysis method of developmental discrepancies led to controversy regarding the nature of SLD. Is the profile of these students unique among this entire population? Does the profile of SLD subtests significantly differ from other cases with normal intelligence quotients? [25].

In a meta-analysis of studies, Kavale and Forness [17] could not determine a specific WISC-based profile for students with LD, because, despite the imbalances among the subtests or between the verbal and practical part of the criterion, the differences were deemed statistically insignificant. Thus, they argued that "specific" profiles could only be indicative of the children's competencies and incompetencies, an element useful in the planning of pedagogical treatment. Studies with similar results also came to the same conclusion [26]. Failure to identify intra-individual discrepancies of cognitive abilities reinforced the notion that discrepancies could be identified between intelligence and performance indices, a feature that is first introduced in the field's delineation by Bateman's definition [27].

Gradually, this criterion of ability and achievement has become a dominant feature in the identification of SLD. The main problem with this approach was that, while the WISC test remained the constant criterion for the intelligence quotient (IQ ), achievement was being assessed with various formal and informal criteria. For this reason, the discrepancy criterion was disputed [28]. A further reason of doubt was that meta-analyses of studies determined a change in the rate of students with LD when different criteria were applied. For example, analyses of findings in the state of Colorado showed that 26% of students did not meet the criterion, while 30% only did so in reading and maths. By applying a different criterion for achievement among the same sample, 5% of students met the criterion in maths and 27% in reading [28]. In another meta-analysis of findings, Cone, Wilson, and Bradley found that, in the state of Iowa, 75% met the discrepancy criterion [29]. In a similar study, Kavale and Reese [30] noted discrepancy rates between 33% and 75% depending on the tests being used. Thus, Lyon et al. came to the conclusion that discrepancy as a primary criterion of determining LD is more harmful than beneficial for children, because achievement criteria involve various external factors, such as the educator, the infrastructure, the curriculum, etc.; these factors can neither be isolated nor interpret the complex interactions between "deficit" and pedagogical/social factors, which need to be taken into consideration during the diagnostic procedure [31].

**9**

*Concepts and Ambiguities in the Field of Learning Disabilities*

adaptive skill deficits and those who have SLD [42].

the field, LD cannot represent a scientific entity.

**3. Contemporary frameworks to identify LD**

In summary, it seems obvious that lack of consensus among scholars, researchers, and practitioners regarding the key elements which distinguish the LD category from other low-achievement categories, as well as the lack of common understanding of their nature and causes, has led the field to stagnation. Two contradictory positions in the general debate exist. One identifies disabilities with the innatespecific learning inadequacies of these students, while the other considers them an "umbrella" category, which covers a wide range of students with low achievement without developmental specificities. For those supporting the "umbrella" characterization, LD is a construct of the modern educational system, which, according to Senf [38], has tried to purify general education like a sociological sponge, which is most "absorbing" when academic demands are rigid or the parents' pressure for achievement is higher. This sponge also absorbs not only the individual differences of students but also a variety of pedagogical, behavioral, and psychosocial problems, which can impede school learning. However, with no scientific delineation of

For this reason, researchers today try to redefine the field of SLD in order to answer the question whether SLD constitute a scientific category or they represent

About 50 years ago, Cruickshank described a vague picture of students with LD as students who are classified differently in each state [32]. The lack of definition of the nature of LD and the ambiguity regarding the causal relationships between learning abilities and academic achievement, but also the question of whether they represent a specific disorder and what that means, led to overgeneralisations of the term, with all children with difficulties in academic achievement to be thought of presenting LD or, on the contrary, to sub-generalizations of the term based on one symptom, which appears in most cases of LD, usually in reading difficulties. It is a fact that 90% of students with LD exhibit reading difficulties [30]. But is this problem primary or secondary? Which cases of reading difficulties might fall within the range of LD? According to studies, children with reading difficulties of various causes are impossible to be distinguished from children who fall within the category of SLD (dyslexia), as stipulated in IDEA's definition [33, 34]. But even in cases of specific reading difficulties, namely, dyslexia, it has been argued that students with this disorder find themselves at the lowest point of the normal distribution of reading ability [35]. Ysseldyke et al., in their study of students who were diagnosed as having LD and students who were not diagnosed but were at the lowest level of the reading ability distribution, found no psychometric differences in the performance of the two groups [36]. Based on these results as well as other studies, Algozzine concluded that in general, LD as a category is "non-existent and useless" [33]. Also, the fact that the majority of these children exhibit reading difficulties has led—mainly in Europe—to the equation of LD with dyslexia, which, while representing one of their symptoms, according to IDEA's definition, has ended up becoming an autonomous scientific field. Thus, mainly in Europe, LD have been equated with dyslexia on the basis of the unclear criteria of low reading performance and the exclusionary elements included in all LD definitions. The lack of consensus has led to the development of two trends on an international professional and administrative level. On the one side stand, those who accept SLD as a distinct group [37–40] and, on the other, those who relate them to every student of low academic achievement [41]. In most countries, though, educators apply solely the criterion of excluding low intelligence quotients; that is, they aim to differentiate between students who have an intellectual ability and associated

*DOI: http://dx.doi.org/10.5772/intechopen.90777*

#### *Concepts and Ambiguities in the Field of Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.90777*

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

Even the definitions' points of convergence do not lead to a uniform interpretation of their nature. For this reason, in numerous studies and research, SLD are approached from different perspectives, and different terms are used to describe them, such as learning disabilities, specific learning disabilities, dyslexia, specific language impairment, attention deficit hyperactivity disorder, etc. But in all formal definitions, the element of ability-achievement discrepancy appears constantly. The problem of discrepancy raises a reasonable question: "What is the meaning of concepts such as intelligence or general cognitive ability, learning or cognitive processes, and academic achievement—concepts that are included in every definition of SLD—and what is the causal relationship between them?" [4]. Unless this question is resolved, the identification of the field will remain vague and contentious. Since conceptual and scientific definitions did not facilitate the identification of the SLD field, an operational description of the condition was required for practical implementation. The phenomenon of intra-individual differences was first studied, particularly the possibility of some "malfunctioning" of certain abilities in contrast to the normal development of others. These developmental imbalances could become apparent in discrepancies of intelligence functions, which are included in intelligence testing, such as the Wechsler Intelligence Scale for Children (WISC). WISC composites can be used to identify profiles of strengths and weaknesses, which can distinguish students with SLD from other groups of students with average or low overall intelligence function scores. This analysis method of developmental discrepancies led to controversy regarding the nature of SLD. Is the profile of these students unique among this entire population? Does the profile of SLD subtests

significantly differ from other cases with normal intelligence quotients? [25]. In a meta-analysis of studies, Kavale and Forness [17] could not determine a specific WISC-based profile for students with LD, because, despite the imbalances among the subtests or between the verbal and practical part of the criterion, the differences were deemed statistically insignificant. Thus, they argued that "specific" profiles could only be indicative of the children's competencies and incompetencies, an element useful in the planning of pedagogical treatment. Studies with similar results also came to the same conclusion [26]. Failure to identify intra-individual discrepancies of cognitive abilities reinforced the notion that discrepancies could be identified between intelligence and performance indices, a feature that is first

Gradually, this criterion of ability and achievement has become a dominant feature in the identification of SLD. The main problem with this approach was that, while the WISC test remained the constant criterion for the intelligence quotient (IQ ), achievement was being assessed with various formal and informal criteria. For this reason, the discrepancy criterion was disputed [28]. A further reason of doubt was that meta-analyses of studies determined a change in the rate of students with LD when different criteria were applied. For example, analyses of findings in the state of Colorado showed that 26% of students did not meet the criterion, while 30% only did so in reading and maths. By applying a different criterion for achievement among the same sample, 5% of students met the criterion in maths and 27% in reading [28]. In another meta-analysis of findings, Cone, Wilson, and Bradley found that, in the state of Iowa, 75% met the discrepancy criterion [29]. In a similar study, Kavale and Reese [30] noted discrepancy rates between 33% and 75% depending on the tests being used. Thus, Lyon et al. came to the conclusion that discrepancy as a primary criterion of determining LD is more harmful than beneficial for children, because achievement criteria involve various external factors, such as the educator, the infrastructure, the curriculum, etc.; these factors can neither be isolated nor interpret the complex interactions between "deficit" and pedagogical/social factors, which need to be taken into consideration during the diagnostic procedure [31].

introduced in the field's delineation by Bateman's definition [27].

**8**

About 50 years ago, Cruickshank described a vague picture of students with LD as students who are classified differently in each state [32]. The lack of definition of the nature of LD and the ambiguity regarding the causal relationships between learning abilities and academic achievement, but also the question of whether they represent a specific disorder and what that means, led to overgeneralisations of the term, with all children with difficulties in academic achievement to be thought of presenting LD or, on the contrary, to sub-generalizations of the term based on one symptom, which appears in most cases of LD, usually in reading difficulties. It is a fact that 90% of students with LD exhibit reading difficulties [30]. But is this problem primary or secondary? Which cases of reading difficulties might fall within the range of LD? According to studies, children with reading difficulties of various causes are impossible to be distinguished from children who fall within the category of SLD (dyslexia), as stipulated in IDEA's definition [33, 34]. But even in cases of specific reading difficulties, namely, dyslexia, it has been argued that students with this disorder find themselves at the lowest point of the normal distribution of reading ability [35]. Ysseldyke et al., in their study of students who were diagnosed as having LD and students who were not diagnosed but were at the lowest level of the reading ability distribution, found no psychometric differences in the performance of the two groups [36]. Based on these results as well as other studies, Algozzine concluded that in general, LD as a category is "non-existent and useless" [33]. Also, the fact that the majority of these children exhibit reading difficulties has led—mainly in Europe—to the equation of LD with dyslexia, which, while representing one of their symptoms, according to IDEA's definition, has ended up becoming an autonomous scientific field. Thus, mainly in Europe, LD have been equated with dyslexia on the basis of the unclear criteria of low reading performance and the exclusionary elements included in all LD definitions.

The lack of consensus has led to the development of two trends on an international professional and administrative level. On the one side stand, those who accept SLD as a distinct group [37–40] and, on the other, those who relate them to every student of low academic achievement [41]. In most countries, though, educators apply solely the criterion of excluding low intelligence quotients; that is, they aim to differentiate between students who have an intellectual ability and associated adaptive skill deficits and those who have SLD [42].

In summary, it seems obvious that lack of consensus among scholars, researchers, and practitioners regarding the key elements which distinguish the LD category from other low-achievement categories, as well as the lack of common understanding of their nature and causes, has led the field to stagnation. Two contradictory positions in the general debate exist. One identifies disabilities with the innatespecific learning inadequacies of these students, while the other considers them an "umbrella" category, which covers a wide range of students with low achievement without developmental specificities. For those supporting the "umbrella" characterization, LD is a construct of the modern educational system, which, according to Senf [38], has tried to purify general education like a sociological sponge, which is most "absorbing" when academic demands are rigid or the parents' pressure for achievement is higher. This sponge also absorbs not only the individual differences of students but also a variety of pedagogical, behavioral, and psychosocial problems, which can impede school learning. However, with no scientific delineation of the field, LD cannot represent a scientific entity.

#### **3. Contemporary frameworks to identify LD**

For this reason, researchers today try to redefine the field of SLD in order to answer the question whether SLD constitute a scientific category or they represent one of the groups with lower achievement, not in need of a special treatment or specially designed instruction. As recently argued [43, 44], the field delineation should summarize all the pre-existing knowledge reflected in the various definitions and the applied pedagogical practices; this will help identify the degree of the deficiency's contribution as well as the contribution of influences by a variety of exogenous factors.

In the USA, educational reform efforts have placed emphasis on the application of evidence-based instructional approaches with the aim of improving the instruction of reading, which has been the focus of research both in the USA and internationally for over 30 years. A major concern that emerged from research was the failure of educational systems to close the gap between children, particularly those with disabilities and those belonging to minorities [45].

Despite the redefinitions and educational regulations, there are still ambiguities and contradictions regarding the conceptualisation and identification of LD. Although there have been attempts to determine why they exist, and many neurobiological researchers have tried to attribute them to disorders of the central nervous system (CNS), so far their causes have not been established [18, 46]. The identification framework of intelligence-achievement discrepancy is still used internationally by those who view LD as a distinct disorder, while the lowachievement model is applied by those who talk of a non-distinct group of low achieving students.

In the USA, school districts in various states have started supplementing the traditional model of testing (e.g. intelligence-achievement discrepancy) with RTI. As aforementioned RTI is considered a viable method for identifying students with LD. In a national survey, 72% of teachers and 54% of parents were in favor of this decision, mainly because RTI's approach facilitates early intervention and pre-referral services [47]. This way, inappropriate referrals to special education are reduced, and at the same time preventative intervention model is created for students who otherwise been referred for special education services after they demonstrated school failure. In recent years, another framework—the pattern of strengths and weaknesses (PSW)—has emerged with the tendency to prevail; although not covered by federal law regulations, it is widely accepted and used in the USA because it supports research-based practices [40, 48].

Thus, depending on the theoretical approaches toward LD, today there are four framework models that can be used for the conceptualisation and identification of SLD, especially in the USA [41]. Proponents of the non-distinctive nature of the disorder have adopted the *low-achievement framework*, which does not take into account the element of unexpected underachievement. Proponents of the distinctive nature of the disorder use one or more of the three remaining frameworks: *intelligence-achievement discrepancy*, *response to instruction-intervention*, and *intra-individual differences* (PSW) [49]. A key element to the disorder's distinctive character is the concept of unexpected underachievement; this is presented by children which should be able to learn but cannot demonstrate scholastic success, without the existence of other learning obstacles, and while receiving adequate instruction. Therefore, the key aspect in assessing the identification's validity is to determine which of the frameworks produce a unique group of low achievers [31]. A valid classification should reflect measurements that provide functionality to the construct of unexpected underachievement [50].

The traditional framework of intelligence-achievement discrepancy (IAD) remains dominant in the identification both in the USA and internationally, despite the controversy it has provoked. It is a determining method of identifying students with SLD when they present significant discrepancy between cognitive ability, as typically measured by IQ, and academic achievement, as measured by standardized

**11**

*Concepts and Ambiguities in the Field of Learning Disabilities*

reading, writing, and mathematical tests [51]. This framework has been criticized for its reliability both in terms of aptitude tests and achievement tests, due to the multidimensional nature of LD and the errors in psychometric measurements. Response to intervention (RTI) is another framework which, as mentioned, facilitates instruction both in general education and specific interventions for students who do not meet the core curriculum level. In order for a student to be considered at risk for academic difficulties, the student's assessments are compiled, and his or her progress is monitored after specific interventions. Following the implementation of interventions, when there is still discrepancy in achievement and growth, then the student is considered to have LD [52]. This model is used in the USA, while another similar pedagogical model of dynamic assessment is used in Britain. This framework has also received criticism, on the grounds that the use of multiple assessments in class to identify students with lower achievement in each subject is an unstable method, always depending on the group comprising the class. With the use of either a single test or the scores in multiple tests, it is hard to notice the latent of a student's abilities and determine the cut-point that would place him

As it has been said that the framework of the pattern of strengths and weaknesses is allowed under the provision of alternative research-based practices in the IDEA. There are different PSW models, like the concordance-disconcordance model [44], the dual discrepancy/consistency model (also referred to as crossbattery assessment; [40]), and the discrepancy/consistency model [48]. These three models differ in methodology, but they converge on the fact that students can be identified as having SLD when they demonstrate unexpected academic underachievement and corresponding weakness in one or more specific cognitive abilities related to the area of the academic deficit [53]. However, in practice, students can be often identified with SDL through demonstration of a pattern of strengths and weaknesses only in academic achievement domains [49]. Moreover, multiple individual differences might be present, which accumulate the errors of measurements

In a recent survey regarding the frameworks being used by school psychologists in the USA, Cottrell and Barrett [54], looking at a sample of 471 school psychologists, found out that 63.1% were almost always using the intelligence-achievement discrepancy (IAD) framework. 49.3% were using the RTI framework in most cases, and 29.4% were using the PSW framework in almost every case. However, they could not determine which framework was being primarily employed. For instance, 31.5% reported that they had been using the RTI framework most of the times, while only 17.8% reported that they were using this framework exclusively. In order to find out which one is being primarily employed, Maki and Adams surveyed 461 school psychologists in 2017 [55]. They discovered that only 30.4% reported primarily using the IAD framework, while they were primarily using almost equally

Benson et al. [56], in another national-level US-based survey with 1317 school psychologists, found out that 37% were using IAD, even in states where it is not included in the diagnostic procedure. Fifty-one percent were using RTI [56]. Finally, approximately 53% reported that they were using PSW. In the same survey, 49.2% reported that they were participating in academic screening procedures, which include monitoring of early literacy, oral reading fluency, reading comprehension, early numeracy, math computation, math concepts and applications, spelling, and written expression prompts, according to the age of the students. Many of the participants reported a combined use of RTI and PSW, RTI and IAD, and PSW and IAD. This last survey confirms the lack of consensus regarding identification

the RTI (34.5%) and the PSW (35.1%) framework, respectively.

procedures among professionals in the identification of SLD.

*DOI: http://dx.doi.org/10.5772/intechopen.90777*

or her in the LD group.

and render them unreliable.

#### *Concepts and Ambiguities in the Field of Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.90777*

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

with disabilities and those belonging to minorities [45].

the USA because it supports research-based practices [40, 48].

construct of unexpected underachievement [50].

exogenous factors.

achieving students.

one of the groups with lower achievement, not in need of a special treatment or specially designed instruction. As recently argued [43, 44], the field delineation should summarize all the pre-existing knowledge reflected in the various definitions and the applied pedagogical practices; this will help identify the degree of the deficiency's contribution as well as the contribution of influences by a variety of

In the USA, educational reform efforts have placed emphasis on the application of evidence-based instructional approaches with the aim of improving the instruction of reading, which has been the focus of research both in the USA and internationally for over 30 years. A major concern that emerged from research was the failure of educational systems to close the gap between children, particularly those

Despite the redefinitions and educational regulations, there are still ambiguities and contradictions regarding the conceptualisation and identification of LD. Although there have been attempts to determine why they exist, and many neurobiological researchers have tried to attribute them to disorders of the central nervous system (CNS), so far their causes have not been established [18, 46]. The identification framework of intelligence-achievement discrepancy is still used internationally by those who view LD as a distinct disorder, while the lowachievement model is applied by those who talk of a non-distinct group of low

In the USA, school districts in various states have started supplementing the traditional model of testing (e.g. intelligence-achievement discrepancy) with RTI. As aforementioned RTI is considered a viable method for identifying students with LD. In a national survey, 72% of teachers and 54% of parents were in favor of this decision, mainly because RTI's approach facilitates early intervention and pre-referral services [47]. This way, inappropriate referrals to special education are reduced, and at the same time preventative intervention model is created for students who otherwise been referred for special education services after they demonstrated school failure. In recent years, another framework—the pattern of strengths and weaknesses (PSW)—has emerged with the tendency to prevail; although not covered by federal law regulations, it is widely accepted and used in

Thus, depending on the theoretical approaches toward LD, today there are four framework models that can be used for the conceptualisation and identification of SLD, especially in the USA [41]. Proponents of the non-distinctive nature of the disorder have adopted the *low-achievement framework*, which does not take into account the element of unexpected underachievement. Proponents of the distinctive nature of the disorder use one or more of the three remaining frameworks: *intelligence-achievement discrepancy*, *response to instruction-intervention*, and *intra-individual differences* (PSW) [49]. A key element to the disorder's distinctive character is the concept of unexpected underachievement; this is presented by children which should be able to learn but cannot demonstrate scholastic success, without the existence of other learning obstacles, and while receiving adequate instruction. Therefore, the key aspect in assessing the identification's validity is to determine which of the frameworks produce a unique group of low achievers [31]. A valid classification should reflect measurements that provide functionality to the

The traditional framework of intelligence-achievement discrepancy (IAD) remains dominant in the identification both in the USA and internationally, despite the controversy it has provoked. It is a determining method of identifying students with SLD when they present significant discrepancy between cognitive ability, as typically measured by IQ, and academic achievement, as measured by standardized

**10**

reading, writing, and mathematical tests [51]. This framework has been criticized for its reliability both in terms of aptitude tests and achievement tests, due to the multidimensional nature of LD and the errors in psychometric measurements.

Response to intervention (RTI) is another framework which, as mentioned, facilitates instruction both in general education and specific interventions for students who do not meet the core curriculum level. In order for a student to be considered at risk for academic difficulties, the student's assessments are compiled, and his or her progress is monitored after specific interventions. Following the implementation of interventions, when there is still discrepancy in achievement and growth, then the student is considered to have LD [52]. This model is used in the USA, while another similar pedagogical model of dynamic assessment is used in Britain. This framework has also received criticism, on the grounds that the use of multiple assessments in class to identify students with lower achievement in each subject is an unstable method, always depending on the group comprising the class. With the use of either a single test or the scores in multiple tests, it is hard to notice the latent of a student's abilities and determine the cut-point that would place him or her in the LD group.

As it has been said that the framework of the pattern of strengths and weaknesses is allowed under the provision of alternative research-based practices in the IDEA. There are different PSW models, like the concordance-disconcordance model [44], the dual discrepancy/consistency model (also referred to as crossbattery assessment; [40]), and the discrepancy/consistency model [48]. These three models differ in methodology, but they converge on the fact that students can be identified as having SLD when they demonstrate unexpected academic underachievement and corresponding weakness in one or more specific cognitive abilities related to the area of the academic deficit [53]. However, in practice, students can be often identified with SDL through demonstration of a pattern of strengths and weaknesses only in academic achievement domains [49]. Moreover, multiple individual differences might be present, which accumulate the errors of measurements and render them unreliable.

In a recent survey regarding the frameworks being used by school psychologists in the USA, Cottrell and Barrett [54], looking at a sample of 471 school psychologists, found out that 63.1% were almost always using the intelligence-achievement discrepancy (IAD) framework. 49.3% were using the RTI framework in most cases, and 29.4% were using the PSW framework in almost every case. However, they could not determine which framework was being primarily employed. For instance, 31.5% reported that they had been using the RTI framework most of the times, while only 17.8% reported that they were using this framework exclusively. In order to find out which one is being primarily employed, Maki and Adams surveyed 461 school psychologists in 2017 [55]. They discovered that only 30.4% reported primarily using the IAD framework, while they were primarily using almost equally the RTI (34.5%) and the PSW (35.1%) framework, respectively.

Benson et al. [56], in another national-level US-based survey with 1317 school psychologists, found out that 37% were using IAD, even in states where it is not included in the diagnostic procedure. Fifty-one percent were using RTI [56]. Finally, approximately 53% reported that they were using PSW. In the same survey, 49.2% reported that they were participating in academic screening procedures, which include monitoring of early literacy, oral reading fluency, reading comprehension, early numeracy, math computation, math concepts and applications, spelling, and written expression prompts, according to the age of the students. Many of the participants reported a combined use of RTI and PSW, RTI and IAD, and PSW and IAD. This last survey confirms the lack of consensus regarding identification procedures among professionals in the identification of SLD.

### **4. Conclusions**

In order to summarize the international research effort, it seems that scientists concur that LD represent a distinct group of students with low academic achievement, regardless of the terms used to describe them (dyslexia, learning difficulties, special learning difficulties, special reading difficulties, etc.). They also agree that it is a matter of developmental disorder with implications across the life span. As a developmental problem, LD follow a course from the beginning of life and are determined by the interaction of innate factors with the environment, much like development itself. LD do not comprise a distinguishable entity like other developmental phenomena but a combination of traits; their common element is the existence of discrepancies in cognitive function and achievement, and they appear to be incompatible with social and cultural demands and expectations. The source of their heterogeneity is not exclusively biological or environmental but rather a product of synergy between biological and social processes, which promote development and contribute to the formation of these functional systems. It may never be possible to find a dividing line or a criterion that distinguishes students with SLD from those with an overall low performance. The controversy between scientists may carry on. Decisions are not always based on scientific but mainly social, economic, and political reasons. It is widely accepted that the root of LD is a disorder that already exists within the child; however, it is the child's interaction with the world around him or her that shapes how this disorder manifests. Such a systemic perspective demands an exhaustive understanding and an interdisciplinary approach. A lot remains unresolved before we can answer the questions regarding the nature and interpretation of LD. We know a lot from empirical data, but we are not in the position to complete the puzzle and provide an answer to the main question which has to do with the field's identification. Until then, we must continue to assess and fully understand the developmental path of each child and to take into account all the factors involved in the development of learning disabilities.

### **Author details**

Maria Tzouriadou School of Early Childhood Education, Aristotle University of Thessaloniki, Thessaloniki, Greece

\*Address all correspondence to: tzour@nured.auth.gr

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**13**

*Concepts and Ambiguities in the Field of Learning Disabilities*

ICAA Word Blind Centre for Dyslexic Children. London: Pitman; 1972

[11] Miles TR. Understanding Dyslexia. London: Hodder and Stoughtn; 1978

[12] Rutter M. The concept of dyslexia. In: Wolffand H, MacKeith R, editors. Planning for Better Learning. London:

[13] Rutter M, Tizard J, Whitmore K, editors. Education, Health and Behaviour. London: Longman Green;

[14] Report W. Special Educational Needs. Report of the Committee of Enquiry into the Education of Handicapped Children and Young People. London: Her Majesty's

[15] National Joint Committee on Learning Disabilities. Letter from NJCLD to Member Organizations. Topic: Modifications to the NJCLD Definition of Learning Disabilities; 1989

[16] Kavale KA, Spaulding LS, Beam AP. A time to define: Making the specific learning disability definition prescribe specific learning disability. Learning Disability Quarterly. 2009;**1**:39-48.

[17] Kavale KA, Forness SR. A metaanalysis of the validity of Wechler scale profiles and recategorizations: Patterns of parodies? Learning Disabilities Quarterly. 1984;**7**:136-156. DOI:

[18] Individuals with Disabilities Education Improvement Act [IDEIA]. Pub. L. No. 108-446, 118 Stat. 2647.

Their consequences for research and policy. In: Benton AL, Pearl D,

[19] Eisenberg L. Definitions of dyslexia:

Heinemann; 1969. p. 129

Stationery Office; 1978

DOI: 10.2307/25474661

10.2307/1510314

2004

1970

*DOI: http://dx.doi.org/10.5772/intechopen.90777*

[2] Doris J. Defining learning disabilities: A history of the search for consensus. In: Lyon GR, Gray DB, Kavanagh JF, editors. Better Understanding Learning Disabilities. Baltimore: Brooks; 1993.

[1] Cattell RB. The time taken up by cerebral operations. Mind. 1886;**11**:

[3] National Center for Learning Disabilities (NCLD). Learning Disability Fast Facts. 2011. Available

ld-explained/basic-facts/ld-fast-facts

Disabilities: Issues of Identification and Identification. Prometheus: Thessaloniki;

[5] Kirk SA. Educating Exceptional Children. Boston: Houghton Mifflin;

[6] National Advisory Committee on Handicapped Children (NACHC). Special Education for Handicapped Children (First Annual Report). Washington, DC: Department of Health, Education, and Welfare; 1968

[7] Individuals with Disability Education Act Amendments of 1997 [IDEA]. 1997. Available from: https://www.congress. gov/105/plaws/publ17/PLAW-105publ17.

[8] Arkell H. The Edith Norrie Letter Case. London: Helen Arkell Centre; 1973

[9] Wepman JM, Cruickshank WM, Deutsch CP, Morency AS, Strother GR. Learning disabilities. In: Hobbs N, editor. Issues in the Classification of Children. Vol. 1. San Francisco: Jossey-

[10] The CM, Child D, Naidoo S. Specific Dyslexia: The Research Report of the

Bass; 1975. pp. 300-317

from: www.ld.org/ld-basics/

[4] Tzouriadou M. Learning

220-242, 377-392, 524-538

pp. 97-116

**References**

2011

1962

pdf

*Concepts and Ambiguities in the Field of Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.90777*

#### **References**

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

School of Early Childhood Education, Aristotle University of Thessaloniki,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: tzour@nured.auth.gr

provided the original work is properly cited.

In order to summarize the international research effort, it seems that scientists concur that LD represent a distinct group of students with low academic achievement, regardless of the terms used to describe them (dyslexia, learning difficulties, special learning difficulties, special reading difficulties, etc.). They also agree that it is a matter of developmental disorder with implications across the life span. As a developmental problem, LD follow a course from the beginning of life and are determined by the interaction of innate factors with the environment, much like development itself. LD do not comprise a distinguishable entity like other developmental phenomena but a combination of traits; their common element is the existence of discrepancies in cognitive function and achievement, and they appear to be incompatible with social and cultural demands and expectations. The source of their heterogeneity is not exclusively biological or environmental but rather a product of synergy between biological and social processes, which promote development and contribute to the formation of these functional systems. It may never be possible to find a dividing line or a criterion that distinguishes students with SLD from those with an overall low performance. The controversy between scientists may carry on. Decisions are not always based on scientific but mainly social, economic, and political reasons. It is widely accepted that the root of LD is a disorder that already exists within the child; however, it is the child's interaction with the world around him or her that shapes how this disorder manifests. Such a systemic perspective demands an exhaustive understanding and an interdisciplinary approach. A lot remains unresolved before we can answer the questions regarding the nature and interpretation of LD. We know a lot from empirical data, but we are not in the position to complete the puzzle and provide an answer to the main question which has to do with the field's identification. Until then, we must continue to assess and fully understand the developmental path of each child and to take into account all the factors involved in the development of learning disabilities.

**4. Conclusions**

**12**

**Author details**

Maria Tzouriadou

Thessaloniki, Greece

[1] Cattell RB. The time taken up by cerebral operations. Mind. 1886;**11**: 220-242, 377-392, 524-538

[2] Doris J. Defining learning disabilities: A history of the search for consensus. In: Lyon GR, Gray DB, Kavanagh JF, editors. Better Understanding Learning Disabilities. Baltimore: Brooks; 1993. pp. 97-116

[3] National Center for Learning Disabilities (NCLD). Learning Disability Fast Facts. 2011. Available from: www.ld.org/ld-basics/ ld-explained/basic-facts/ld-fast-facts

[4] Tzouriadou M. Learning Disabilities: Issues of Identification and Identification. Prometheus: Thessaloniki; 2011

[5] Kirk SA. Educating Exceptional Children. Boston: Houghton Mifflin; 1962

[6] National Advisory Committee on Handicapped Children (NACHC). Special Education for Handicapped Children (First Annual Report). Washington, DC: Department of Health, Education, and Welfare; 1968

[7] Individuals with Disability Education Act Amendments of 1997 [IDEA]. 1997. Available from: https://www.congress. gov/105/plaws/publ17/PLAW-105publ17. pdf

[8] Arkell H. The Edith Norrie Letter Case. London: Helen Arkell Centre; 1973

[9] Wepman JM, Cruickshank WM, Deutsch CP, Morency AS, Strother GR. Learning disabilities. In: Hobbs N, editor. Issues in the Classification of Children. Vol. 1. San Francisco: Jossey-Bass; 1975. pp. 300-317

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[18] Individuals with Disabilities Education Improvement Act [IDEIA]. Pub. L. No. 108-446, 118 Stat. 2647. 2004

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editors. Dyslexia: An Appraisal of Current Knowledge. New York: Oxford University Press; 1978

[20] National Institute of Child Health and Human Development. Report of the National Reading Panel: Teaching Children to Read: An Evidencebased Assessment of the Scientific Research Literature on Reading and Its Implications for Reading Instruction: Reports of the Subgroups (NIH Publication No. 00-4754). Washington, DC: U.S. Government Printing Office; 2000

[21] US. Department of Education. No Child Left Behind. 2004. Available from: http://www.ed.gov/nclb/landing. jhtml

[22] Donovan MS, Cross CT. Minority Students in Special and Gifted Education. Washington, DC: National Academy Press; 2002. Available from: http://www.nap.edu/catalog/10128.html

[23] American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013

[24] Hallahan DP, Mercer CD. Learning Disabilities: Historical Perspectives. Washington, DC: US Department of Education, Office of Special Education Programs; 2001

[25] Kaufman AS. The WISC-R and learning disabilities assessment: State of the art. Journal of Learning Disabilities. 1981;**14**:520-526

[26] Naglieri JA. Factor structure of the WISC-R for children identified as learning disabled. Psychological Reports. 1981;**49**:891-895. DOI: 10.2466/pr0.1981.49.3.891

[27] Bateman B. An educator's view of a diagnostic approach to learning disorders. In: Hellmuth J, editor. Learning Disorders. Vol. 1. Seattle:

Special Child Publication; 1965. pp. 219-239

[28] Shepard LA, Smith ML, Vojir CP. Characteristics of pupils identified as learning disabled. American Educational Research Journal. 1983;**20**:309-331. DOI: 10.3102/00028312020003309

[29] Cone TE, Wilson LR, Bradley CM, Reese JH. Characteristics of LD students in Iowa: An empirical investigation. Learning Disability Quarterly. 1985;**8**:211-220

[30] Kavale KA, Reese JH. The character of learning disabilities: An Iowa profile. Learning Disability Quarterly. 1992;**15**:74-94. DOI: 10.2307/1511010

[31] Lyon GR, Shaywitz JM, Shaywitz BA, Torgesen JK, Wood FB, Schulte A, et al. Rethinking learning disabilities. In: Finn CE, Rotherham AJ, Hokanson C Jr, editors. Rethinking Special Education for a New Century. Washington DC: Thomas B. Fordham Foundation and Progressive Policy Institute; 2001. pp. 259-287

[32] Cruickshank WM. The Brain-Injured Child in Home, School, and Community. Syracuse, NY: Syracuse University Press; 1967

[33] Algozzine B. Low achiever differentiation: Where's the beef? Article Commentary. 1985;**52**:72-75. DOI: 10.1177/001440298505200109

[34] Fletcher JM, Shaywitz SE, Shankweiler DP, Katz L, Liberman IY, Stuebing KK, et al. Cognitive profiles of reading disability: Comparisons of discrepancy and low achievement definitions. Journal of Educational Psychology. 1994;**86**:6-23

[35] Shaywitz SE, Fletcher JM, Hallahan JM, Schneider AE, Marchione KE, Stuebing KK, et al. Persistence of dyslexia: The Connecticut

**15**

*Concepts and Ambiguities in the Field of Learning Disabilities*

[43] Waber DP. Rethinking Learning Disabilities: Understanding Children Who Struggle in School. New York:

[44] Hale JB, Alfonso V, Berninger B, Bracken B, Christo C, Clark E, et al. Critical issues in response-tointervention, comprehensive evaluation, and specific learning disabilities identification and intervention: An expert white paper consensus. Learning Disability Quarterly. 2010;**33**(3):223-236

[45] Lemons CJ, Fuchs D, Gilbert GK, Fuchs LS. Evidence-based practices in a changing world: Reconsidering the counterfactual in education research. Educational Researcher. 2014;**43**:242- 252. DOI: 10.3102/0013189X14539189

[46] American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders—Text Revision. 4th ed. Washington, DC: Author; 2000

[47] National Center for Learning Disabilities (NCLD). Early Help for Struggling Learners: A National Survey of Parents and Educators. Author; 2002. Available from: http://www.ld.org/ press/PR2003/survey\_findings.pdf

[48] Naglieri JA, Feifer SG. Pattern of strengths and weaknesses made easy: The discrepancy/consistency method. In: Alfonso VC, Flanagan DP, editors. Essentials of Specific Learning Disability Identification. Hoboken, NJ:

Wiley; 2018. pp. 431-474

[49] Fletcher JM, Miciak J. The Identification of Specific Learning Disabilities: A Summary of Research on Best Practices. Texas Center for Learning Disabilities: Houston University of Houston; 2019

[50] Stuebing KK, Fletcher JM,

LeDoux JM. Validity of IQ-discrepancy classifications of reading disabilities: A meta-analysis. American Educational

Guilford Press; 2010

*DOI: http://dx.doi.org/10.5772/intechopen.90777*

longitudinal study at adolescence. Pediatrics. 1999;**104**:1351-1359

Shinn MR, McGue M. Similarities and differences between low achievers and students classified learning disabled. Journal of Special Educatio.

[36] Ysseldyke JE, Algozzine B,

[37] Kirk SA. Illinois test of

Child Publications; 1968

psycholinguistic abilities: Its origin and implication. In: Hellmut J, editor. Learning Disorders. Seattle: Special

[38] Senf GM. LD research in sociological and scientific perspective. In: Torgesen JK, Wong BYL, editors. Psychological and Educational Perspectives on Learning Disabilities. New York: Academic Press;

[39] Naglieri J, Bornstein B. Intelligence and achievement: Just how correlated are they? Journal of Psychoeducational Assessment. 2003;**21**:244-260. DOI: 10.1177/073428290302100302

[40] Flanagan DP, Alfonso VC, Sy MC, Mascolo JT, McDonough EM, Ortiz SO. Dual discrepancy/consistency

operational definition of SLD: Integrating multiple data sources and multiple data-gathering methods. In: Alfonso VC, Flanagan DP, editors. Essentials of Specific Learning

Wiley; 2018. pp. 329-430

[42] Fletcher JM, Coulter WA, Reschly DJ, Vaughn S. Alternative approaches to the definition and identification of learning disabilities: Some questions and answers. Annals of

Dyslexia. 2004;**54**:304-331

Disability Identification. Hoboken, NJ:

[41] Hallahan DP, Pullen PC, Ward D. A brief history of the field of learning disabilities. In: Swanson H, Harris KR, Graham S, editors. Handbook of Learning Disabilities. New York, NY: The Guilford Press; 2013. pp. 15-32

1982;**16**:73-85

1986. pp. 27-53

#### *Concepts and Ambiguities in the Field of Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.90777*

longitudinal study at adolescence. Pediatrics. 1999;**104**:1351-1359

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

Special Child Publication; 1965.

[29] Cone TE, Wilson LR, Bradley CM, Reese JH. Characteristics of LD students in Iowa: An empirical investigation. Learning Disability Quarterly.

[30] Kavale KA, Reese JH. The character

Shaywitz BA, Torgesen JK, Wood FB, Schulte A, et al. Rethinking learning disabilities. In: Finn CE, Rotherham AJ, Hokanson C Jr, editors. Rethinking Special Education for a New Century. Washington DC: Thomas B. Fordham Foundation and Progressive Policy

of learning disabilities: An Iowa profile. Learning Disability Quarterly. 1992;**15**:74-94. DOI: 10.2307/1511010

[31] Lyon GR, Shaywitz JM,

Institute; 2001. pp. 259-287

University Press; 1967

[32] Cruickshank WM. The Brain-Injured Child in Home, School, and Community. Syracuse, NY: Syracuse

[33] Algozzine B. Low achiever differentiation: Where's the beef? Article Commentary. 1985;**52**:72-75. DOI: 10.1177/001440298505200109

[34] Fletcher JM, Shaywitz SE,

Psychology. 1994;**86**:6-23

[35] Shaywitz SE, Fletcher JM, Hallahan JM, Schneider AE, Marchione KE, Stuebing KK, et al. Persistence of dyslexia: The Connecticut

Shankweiler DP, Katz L, Liberman IY, Stuebing KK, et al. Cognitive profiles of reading disability: Comparisons of discrepancy and low achievement definitions. Journal of Educational

[28] Shepard LA, Smith ML, Vojir CP. Characteristics of pupils identified as learning disabled. American Educational Research Journal. 1983;**20**:309-331. DOI: 10.3102/00028312020003309

pp. 219-239

1985;**8**:211-220

editors. Dyslexia: An Appraisal of Current Knowledge. New York: Oxford

[20] National Institute of Child Health and Human Development. Report of the National Reading Panel: Teaching Children to Read: An Evidencebased Assessment of the Scientific Research Literature on Reading and Its Implications for Reading Instruction: Reports of the Subgroups (NIH

Publication No. 00-4754). Washington, DC: U.S. Government Printing Office;

[21] US. Department of Education. No Child Left Behind. 2004. Available from: http://www.ed.gov/nclb/landing.

[22] Donovan MS, Cross CT. Minority Students in Special and Gifted

Education. Washington, DC: National Academy Press; 2002. Available from: http://www.nap.edu/catalog/10128.html

[23] American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013

[24] Hallahan DP, Mercer CD. Learning Disabilities: Historical Perspectives. Washington, DC: US Department of Education, Office of Special Education

[25] Kaufman AS. The WISC-R and learning disabilities assessment: State of the art. Journal of Learning Disabilities.

[26] Naglieri JA. Factor structure of the WISC-R for children identified as learning disabled. Psychological Reports. 1981;**49**:891-895. DOI: 10.2466/pr0.1981.49.3.891

[27] Bateman B. An educator's view of a diagnostic approach to learning disorders. In: Hellmuth J, editor. Learning Disorders. Vol. 1. Seattle:

Programs; 2001

1981;**14**:520-526

University Press; 1978

2000

jhtml

**14**

[36] Ysseldyke JE, Algozzine B, Shinn MR, McGue M. Similarities and differences between low achievers and students classified learning disabled. Journal of Special Educatio. 1982;**16**:73-85

[37] Kirk SA. Illinois test of psycholinguistic abilities: Its origin and implication. In: Hellmut J, editor. Learning Disorders. Seattle: Special Child Publications; 1968

[38] Senf GM. LD research in sociological and scientific perspective. In: Torgesen JK, Wong BYL, editors. Psychological and Educational Perspectives on Learning Disabilities. New York: Academic Press; 1986. pp. 27-53

[39] Naglieri J, Bornstein B. Intelligence and achievement: Just how correlated are they? Journal of Psychoeducational Assessment. 2003;**21**:244-260. DOI: 10.1177/073428290302100302

[40] Flanagan DP, Alfonso VC, Sy MC, Mascolo JT, McDonough EM, Ortiz SO. Dual discrepancy/consistency operational definition of SLD: Integrating multiple data sources and multiple data-gathering methods. In: Alfonso VC, Flanagan DP, editors. Essentials of Specific Learning Disability Identification. Hoboken, NJ: Wiley; 2018. pp. 329-430

[41] Hallahan DP, Pullen PC, Ward D. A brief history of the field of learning disabilities. In: Swanson H, Harris KR, Graham S, editors. Handbook of Learning Disabilities. New York, NY: The Guilford Press; 2013. pp. 15-32

[42] Fletcher JM, Coulter WA, Reschly DJ, Vaughn S. Alternative approaches to the definition and identification of learning disabilities: Some questions and answers. Annals of Dyslexia. 2004;**54**:304-331

[43] Waber DP. Rethinking Learning Disabilities: Understanding Children Who Struggle in School. New York: Guilford Press; 2010

[44] Hale JB, Alfonso V, Berninger B, Bracken B, Christo C, Clark E, et al. Critical issues in response-tointervention, comprehensive evaluation, and specific learning disabilities identification and intervention: An expert white paper consensus. Learning Disability Quarterly. 2010;**33**(3):223-236

[45] Lemons CJ, Fuchs D, Gilbert GK, Fuchs LS. Evidence-based practices in a changing world: Reconsidering the counterfactual in education research. Educational Researcher. 2014;**43**:242- 252. DOI: 10.3102/0013189X14539189

[46] American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders—Text Revision. 4th ed. Washington, DC: Author; 2000

[47] National Center for Learning Disabilities (NCLD). Early Help for Struggling Learners: A National Survey of Parents and Educators. Author; 2002. Available from: http://www.ld.org/ press/PR2003/survey\_findings.pdf

[48] Naglieri JA, Feifer SG. Pattern of strengths and weaknesses made easy: The discrepancy/consistency method. In: Alfonso VC, Flanagan DP, editors. Essentials of Specific Learning Disability Identification. Hoboken, NJ: Wiley; 2018. pp. 431-474

[49] Fletcher JM, Miciak J. The Identification of Specific Learning Disabilities: A Summary of Research on Best Practices. Texas Center for Learning Disabilities: Houston University of Houston; 2019

[50] Stuebing KK, Fletcher JM, LeDoux JM. Validity of IQ-discrepancy classifications of reading disabilities: A meta-analysis. American Educational

Research Journal. 2002;**39**(2):469-518. DOI: 10.3102/00028312039002469

[51] Fletcher JM, Lyon GR, Fuchs LS, Barnes MA. Learning Disabilities: From Identification to Intervention. 2nd ed. New York, NY: Guilford Press; 2019

[52] Kovaleski J, VanDerHeyden AM, Shapiro ES. The RTI Approach to Evaluating Learning Disabilities. New York, NY: Guilford Press; 2013

[53] Alston-Abel NL, Berninger VW. Relationships between home literacy practices and school achievement: Implications for consultation and home–school collaboration. Journal of Educational and Psychological Consultation: The Official Journal of the Association for Educational and Psychological Consultants. 2017;**28**(2):164-189. DOI: 10.1080/10474412.2017.1323222

[54] Cottrell JM, Barrett CA. Defining the undefinable: Operationalization of methods to identify specific learning disabilities among practicing school psychologists. Psychology in the Schools. 2016;**53**(2):143-157

[55] Maki KE, Adams SR. A current landscape of specific learning disability identification: Training, practices, and implications. Psychology in the Schools. 2018;**56**:18-31. DOI: 10.1002/pits .22179

[56] Benson NF, Maki KE, Floyd RG, Eckert TL, Kranzler JH, Fefer SA. A national survey of school psychologists' practices identifying specific learning disabilities. School Psychology (Washington, D.C.). 2019;**4**:1-12. DOI: 10.1037/spq0000344

**17**

**Chapter 2**

Disorder

*Işık Görker*

**Abstract**

**1. Introduction**

The Prevalence and Gender

Differences in Specific Learning

Learning process including reading, writing, and arithmetic skills in children requires a normal cognitive development period. The presence of signs of disabilities of these skills needs clinical assessment of a specific learning disorder (SLD), a neurodevelopmental disorder. Specific learning disorder which is defined in DSM-V with three types has various prevalence rates according to age, sex, developmental process, environmental factors, and different assessments applied in studies. Comorbidity with other mental disorders reveals more severe symptoms of it. And also if clinical and educational interventions are not performed, behavioral and emotional symptoms may accompany this diagnosis. In this chapter, studies on the prevalence of specific learning disorder are reviewed by considering these factors.

**Keywords:** specific learning disorder, dyslexia, dyscalculia, prevalence, child

ment, occupational performance, or activities of daily life [3].

Specific learning disorder (SLD) is defined as a neurodevelopmental disorder that includes the difficulties in understanding or learning, problems in writing or written expression, and difficulties in the perception/calculation of the numbers. These problems make the academic performance of the child lower than expected. This disorder is originated from biology affecting the acquisition or perception capabilities of the brain for the verbal and nonverbal information processes. There is an abnormality of cognitive level associated with behavioral findings in its etiology [1]. Therefore, it is defined as a failure to meet approved grade-level standards in listening comprehension, reading comprehension, basic reading and reading fluency skills, written expression, mathematics calculation, and/or mathematics problem-solving, despite age-appropriate learning opportunities and instruction [2]. These deficits are persistent and significantly interfere with academic achieve-

SLD is a multifactorial disorder which has in its etiology a genetic predisposition and family load, developmental and cognitive factors, language spoken, and environmental factors including the level of education and socioeconomic situation. In many studies, gender, level of intelligence, higher family history of learning disabilities, low parental education, the exposure during pregnancy to the use of medicines, exposure to radiation, smoking, infections, hypoxia, complicated deliveries, hypoxia during labor, premature labor, low birth weight, low Apgar

#### **Chapter 2**

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

Research Journal. 2002;**39**(2):469-518. DOI: 10.3102/00028312039002469

[51] Fletcher JM, Lyon GR, Fuchs LS, Barnes MA. Learning Disabilities: From Identification to Intervention. 2nd ed. New York, NY: Guilford Press; 2019

[52] Kovaleski J, VanDerHeyden AM, Shapiro ES. The RTI Approach to Evaluating Learning Disabilities. New York, NY: Guilford Press; 2013

[53] Alston-Abel NL, Berninger VW. Relationships between home literacy practices and school achievement: Implications for consultation and home–school collaboration. Journal of Educational and Psychological Consultation: The Official Journal of the Association for Educational and Psychological Consultants. 2017;**28**(2):164-189. DOI: 10.1080/10474412.2017.1323222

[54] Cottrell JM, Barrett CA. Defining the undefinable: Operationalization of methods to identify specific learning disabilities among practicing school psychologists. Psychology in the Schools. 2016;**53**(2):143-157

[55] Maki KE, Adams SR. A current landscape of specific learning disability identification: Training, practices, and implications. Psychology in the Schools. 2018;**56**:18-31. DOI: 10.1002/pits .22179

[56] Benson NF, Maki KE, Floyd RG, Eckert TL, Kranzler JH, Fefer SA. A national survey of school psychologists' practices identifying specific learning disabilities. School Psychology

(Washington, D.C.). 2019;**4**:1-12. DOI:

10.1037/spq0000344

**16**

## The Prevalence and Gender Differences in Specific Learning Disorder

*Işık Görker*

#### **Abstract**

Learning process including reading, writing, and arithmetic skills in children requires a normal cognitive development period. The presence of signs of disabilities of these skills needs clinical assessment of a specific learning disorder (SLD), a neurodevelopmental disorder. Specific learning disorder which is defined in DSM-V with three types has various prevalence rates according to age, sex, developmental process, environmental factors, and different assessments applied in studies. Comorbidity with other mental disorders reveals more severe symptoms of it. And also if clinical and educational interventions are not performed, behavioral and emotional symptoms may accompany this diagnosis. In this chapter, studies on the prevalence of specific learning disorder are reviewed by considering these factors.

**Keywords:** specific learning disorder, dyslexia, dyscalculia, prevalence, child

#### **1. Introduction**

Specific learning disorder (SLD) is defined as a neurodevelopmental disorder that includes the difficulties in understanding or learning, problems in writing or written expression, and difficulties in the perception/calculation of the numbers. These problems make the academic performance of the child lower than expected. This disorder is originated from biology affecting the acquisition or perception capabilities of the brain for the verbal and nonverbal information processes. There is an abnormality of cognitive level associated with behavioral findings in its etiology [1]. Therefore, it is defined as a failure to meet approved grade-level standards in listening comprehension, reading comprehension, basic reading and reading fluency skills, written expression, mathematics calculation, and/or mathematics problem-solving, despite age-appropriate learning opportunities and instruction [2]. These deficits are persistent and significantly interfere with academic achievement, occupational performance, or activities of daily life [3].

SLD is a multifactorial disorder which has in its etiology a genetic predisposition and family load, developmental and cognitive factors, language spoken, and environmental factors including the level of education and socioeconomic situation. In many studies, gender, level of intelligence, higher family history of learning disabilities, low parental education, the exposure during pregnancy to the use of medicines, exposure to radiation, smoking, infections, hypoxia, complicated deliveries, hypoxia during labor, premature labor, low birth weight, low Apgar

score, neonatal jaundice, convulsions, developmental delay, low-income families, and low socioeconomic status, leading to the occurrence of the SLD, are defined as predeterminants [4–11]. In the clinical examination of SLD, children's developmental, medical, educational, and family history are assessed. Test scores and teacher observations and response to academic interventions are also evaluated. For SLD, current academic skills must be well below the average range of expected scores given the person's chronological age (e.g., at least 1.5 standard deviations (SD)) below the population mean for age and age-appropriate education in culturally and linguistically appropriate tests of reading, writing, and/or mathematics [2, 3, 12] with normal levels of intelligence functioning (considering an intellectual coefficient (IQ ) score greater than 70) [1]. These problems cannot be explained with mental retardation, loss of sense (vision or hearing), other psychiatric or neurological disorder, psychosocial difficulties, insufficiency of the language to be used in the academic environment, or education problems. The types like reading disorder (dyslexia), written expression disorder (dysgraphia), and mathematics disorder (dyscalculia) can be seen together or separately.

SLD are usually apparent in the early years of school; some children can show great learning difficulties later on, enabling diagnosis to be made at any point after formal education starts and in adolescence and even adulthood [1]. If treatment approaches are not initiated at an early age, the lives of children and adolescents with SLD are adversely affected due to academic failure. In almost 40% of cases dropout of school. Due to low academic failure, lack of self-confidence, social and behavioral problems may cause emotional problems. This can lead to anxiety disorders, depressive symptoms, somatic complaints, adaptation problems, and difficulties in maintaining a permanent job in the future [1, 13–16].

#### **2. The prevalence rates evaluated in studies of specific learning disorder**

The number of the prevalence studies with diagnostic criteria or scales for SLD is low. On the other hand, SLD is accepted as relatively frequent and is not known sufficiently [17–19]. There have been many studies on SLD from the past to today, and different ratios have been announced on the prevalence. The frequency and prevalence of the SLD are stated in various reports with different rates depending on the size of the sample and the inclusion criteria. For example, Al-Yagon et al. reported different prevalence rates that included 1.2% from Greek epidemiologic study in 2004 and 20.0% from a study in Australia in 2000 [20]. A lifelong prevalence estimative of learning disability was found to be 9.7% in children from 3 to 17 years of age by the 2003 National Survey of Children's Health (NSCH) in the USA [4]. The study in Finland in 2001 reported a prevalence of 21.2% in schoolaged children referred to special education [15]. Del'Homme et al. reported this prevalence of 28.0% in 2004 [21]. In an epidemiological study with 2174 primary school children in Turkey by using checklists, the probable prevalence rates were found to be 13.6% [7]. An important problem that is making the performance of the epidemiological studies harder is the lack of generally accepted definitions or diagnostic criteria for SLD and evaluations based only on a scale or other assessments that measure the level of academic achievement. DSM-V located the diagnosis of SLD into the category of neurodevelopmental disorders and included severity ratings for its assessment. This means that SLD is conceptualized as a dimensional developmental disorder that occurred as a result of multiple risk factors interacting with each other. One of the important changes is the elimination of IQ-achievement discrepancy criterion in DSM-V despite the exclusion criterion of intellectual disability. IQ-discrepancy criterion was taken into consideration in DSM-IV criteria, so

**19**

*The Prevalence and Gender Differences in Specific Learning Disorder*

prevalence rates have found different in studies. For example, in one of the recent studies with 1633 German children in third and fourth grades, the SLD frequency was investigated according to DSM-V criteria, and three different findings were calculated according to the 1, 1.25, and 1.5 standard deviations. Accordingly, the reading disorder for children having 1 as the standard deviation was estimated at 6.49%, written expression disorder was 6.67%, and mathematics disorder was 4.84%; the reading disorder for children having 1.25 as the standard deviation was estimated to be 5.14%, written expression disorder was 6.86%, and mathematics disorder was 3.31%; the reading disorder for children having 1.5 as the standard deviation had an estimated value of 3.8%, written expression disorder was 5.02%, and mathematics disorder was 2.39% [3]. In another study with 1618 Brazilian children and adolescents from second to sixth grades, different prevalence rates were found of SLD by using DSM-IV and DSM-V criteria. These rates were 7.6% for SLD (global) impairment, 5.4% for writing, 6.0% for arithmetic, and 7.5% for reading impairment. The prevalence rates were found to be higher by using DSM-V criteria as they expected [22]. In DSM-V, the American Psychiatric Association reports that the SLD prevalence of children from different languages and cultures is 5–15%, the prevalence of reading disorder is 4–9%, and the prevalence of mathematics disorder is 3–7 [1]. When the reading, writing, and mathematics difficulties were separated, or when reading and mathematics difficulties were grouped together, in studies conducted in different countries, the difficulty rates were found to be different from each other. In previous studies, researchers have suggested that arithmetic and reading functions may depend on similar cognitive predictors [23–25]. It was found that the same phonological processing abilities that are considered to influence growth in reading also appear to contribute to growth in general computation skills [24]. And it was determined that there is a relationship between deficits in processing words and accessing arithmetic facts in long-term memory by Geary [23]. Arithmetical skill is a skill that is based on counting, which involves number words and the use of phonological skills. Because counting involves the activation of number words, the association in long-term memory between problem and answer could be represented, at least in part, in the same phonetic and semantic memory systems that support word recognition. Therefore, it was suggested that the co-occurrence of reading and arithmetic disabilities might reflect a more general deficit in the representation or retrieval of information from semantic memory [26]. The roles of family history and genetic load are considered in reading difficulties and mathematics difficulties, and it is suggested that phonologic problems stated in the etiology of the reading difficulties can create different rates of reading difficulties interculturally, depending on the spoken language. The difficulties in phonemic compliance led to phonologic problems leading to reading difficulties; so, it is suggested that reading difficulties are seen less in countries that have good phoneme-grapheme harmony, and there are higher rates in countries that have poor phoneme-grapheme harmony. Majority of the studies suggested that the prevalence of reading disorder was 5–17% [27]. In the study conducted with 1476 children in 1983, the mathematics disorder rate was 3.6%, and the reading disorder was 2.2% [28]; in the study conducted by Lewis et al. [29] in 1994 with 1056 children who were 9–10 years old, the mathematics disorder was found to be 1.3%, and the reading disorder was 3.9%. In the study conducted by Miles et al. [30] in 1998, the reading disorder prevalence was suggested to be 4.19%, and also in the study of Badian [31] in 1999 with 1075 children, the reading disorder was suggested to be 6%, and the mathematics disorder was suggested to be 3.9%. The studies of Badian [31] and Lewis et al. [29] were designed to obtain an estimation of the prevalence of combined reading and arithmetic, reading only, and arithmetic-only disabilities. Badian found that the prevalence rate in arithmetic and reading was 3.4%, for

*DOI: http://dx.doi.org/10.5772/intechopen.90214*

#### *The Prevalence and Gender Differences in Specific Learning Disorder DOI: http://dx.doi.org/10.5772/intechopen.90214*

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

(dyscalculia) can be seen together or separately.

score, neonatal jaundice, convulsions, developmental delay, low-income families, and low socioeconomic status, leading to the occurrence of the SLD, are defined as predeterminants [4–11]. In the clinical examination of SLD, children's developmental, medical, educational, and family history are assessed. Test scores and teacher observations and response to academic interventions are also evaluated. For SLD, current academic skills must be well below the average range of expected scores given the person's chronological age (e.g., at least 1.5 standard deviations (SD)) below the population mean for age and age-appropriate education in culturally and linguistically appropriate tests of reading, writing, and/or mathematics [2, 3, 12] with normal levels of intelligence functioning (considering an intellectual coefficient (IQ ) score greater than 70) [1]. These problems cannot be explained with mental retardation, loss of sense (vision or hearing), other psychiatric or neurological disorder, psychosocial difficulties, insufficiency of the language to be used in the academic environment, or education problems. The types like reading disorder (dyslexia), written expression disorder (dysgraphia), and mathematics disorder

SLD are usually apparent in the early years of school; some children can show great learning difficulties later on, enabling diagnosis to be made at any point after formal education starts and in adolescence and even adulthood [1]. If treatment approaches are not initiated at an early age, the lives of children and adolescents with SLD are adversely affected due to academic failure. In almost 40% of cases dropout of school. Due to low academic failure, lack of self-confidence, social and behavioral problems may cause emotional problems. This can lead to anxiety disorders, depressive symptoms, somatic complaints, adaptation problems, and

**2. The prevalence rates evaluated in studies of specific learning disorder**

The number of the prevalence studies with diagnostic criteria or scales for SLD is low. On the other hand, SLD is accepted as relatively frequent and is not known sufficiently [17–19]. There have been many studies on SLD from the past to today, and different ratios have been announced on the prevalence. The frequency and prevalence of the SLD are stated in various reports with different rates depending on the size of the sample and the inclusion criteria. For example, Al-Yagon et al. reported different prevalence rates that included 1.2% from Greek epidemiologic study in 2004 and 20.0% from a study in Australia in 2000 [20]. A lifelong prevalence estimative of learning disability was found to be 9.7% in children from 3 to 17 years of age by the 2003 National Survey of Children's Health (NSCH) in the USA [4]. The study in Finland in 2001 reported a prevalence of 21.2% in schoolaged children referred to special education [15]. Del'Homme et al. reported this prevalence of 28.0% in 2004 [21]. In an epidemiological study with 2174 primary school children in Turkey by using checklists, the probable prevalence rates were found to be 13.6% [7]. An important problem that is making the performance of the epidemiological studies harder is the lack of generally accepted definitions or diagnostic criteria for SLD and evaluations based only on a scale or other assessments that measure the level of academic achievement. DSM-V located the diagnosis of SLD into the category of neurodevelopmental disorders and included severity ratings for its assessment. This means that SLD is conceptualized as a dimensional developmental disorder that occurred as a result of multiple risk factors interacting with each other. One of the important changes is the elimination of IQ-achievement discrepancy criterion in DSM-V despite the exclusion criterion of intellectual disability. IQ-discrepancy criterion was taken into consideration in DSM-IV criteria, so

difficulties in maintaining a permanent job in the future [1, 13–16].

**18**

prevalence rates have found different in studies. For example, in one of the recent studies with 1633 German children in third and fourth grades, the SLD frequency was investigated according to DSM-V criteria, and three different findings were calculated according to the 1, 1.25, and 1.5 standard deviations. Accordingly, the reading disorder for children having 1 as the standard deviation was estimated at 6.49%, written expression disorder was 6.67%, and mathematics disorder was 4.84%; the reading disorder for children having 1.25 as the standard deviation was estimated to be 5.14%, written expression disorder was 6.86%, and mathematics disorder was 3.31%; the reading disorder for children having 1.5 as the standard deviation had an estimated value of 3.8%, written expression disorder was 5.02%, and mathematics disorder was 2.39% [3]. In another study with 1618 Brazilian children and adolescents from second to sixth grades, different prevalence rates were found of SLD by using DSM-IV and DSM-V criteria. These rates were 7.6% for SLD (global) impairment, 5.4% for writing, 6.0% for arithmetic, and 7.5% for reading impairment. The prevalence rates were found to be higher by using DSM-V criteria as they expected [22]. In DSM-V, the American Psychiatric Association reports that the SLD prevalence of children from different languages and cultures is 5–15%, the prevalence of reading disorder is 4–9%, and the prevalence of mathematics disorder is 3–7 [1].

When the reading, writing, and mathematics difficulties were separated, or when reading and mathematics difficulties were grouped together, in studies conducted in different countries, the difficulty rates were found to be different from each other. In previous studies, researchers have suggested that arithmetic and reading functions may depend on similar cognitive predictors [23–25]. It was found that the same phonological processing abilities that are considered to influence growth in reading also appear to contribute to growth in general computation skills [24]. And it was determined that there is a relationship between deficits in processing words and accessing arithmetic facts in long-term memory by Geary [23]. Arithmetical skill is a skill that is based on counting, which involves number words and the use of phonological skills. Because counting involves the activation of number words, the association in long-term memory between problem and answer could be represented, at least in part, in the same phonetic and semantic memory systems that support word recognition. Therefore, it was suggested that the co-occurrence of reading and arithmetic disabilities might reflect a more general deficit in the representation or retrieval of information from semantic memory [26]. The roles of family history and genetic load are considered in reading difficulties and mathematics difficulties, and it is suggested that phonologic problems stated in the etiology of the reading difficulties can create different rates of reading difficulties interculturally, depending on the spoken language. The difficulties in phonemic compliance led to phonologic problems leading to reading difficulties; so, it is suggested that reading difficulties are seen less in countries that have good phoneme-grapheme harmony, and there are higher rates in countries that have poor phoneme-grapheme harmony. Majority of the studies suggested that the prevalence of reading disorder was 5–17% [27]. In the study conducted with 1476 children in 1983, the mathematics disorder rate was 3.6%, and the reading disorder was 2.2% [28]; in the study conducted by Lewis et al. [29] in 1994 with 1056 children who were 9–10 years old, the mathematics disorder was found to be 1.3%, and the reading disorder was 3.9%. In the study conducted by Miles et al. [30] in 1998, the reading disorder prevalence was suggested to be 4.19%, and also in the study of Badian [31] in 1999 with 1075 children, the reading disorder was suggested to be 6%, and the mathematics disorder was suggested to be 3.9%. The studies of Badian [31] and Lewis et al. [29] were designed to obtain an estimation of the prevalence of combined reading and arithmetic, reading only, and arithmetic-only disabilities. Badian found that the prevalence rate in arithmetic and reading was 3.4%, for

reading only 6.6%, and for arithmetic only 2.3%. And Lewis reported prevalence proportions as follows: 2.3% for combined reading and arithmetic, 3.9% for reading only, and 1.3% for arithmetic only. When different methods and materials are used in the prevalence studies, different results are obtained as in the studies of Badian and Lewis. While Badian evaluated comprehension in reading, Lewis evaluated word weakness. Although they are both reading processes, they in part require different cognitive skills. Therefore it leads to the identification of a different population of weak readers. Furthermore, another source of variable results across studies is the use of different cutoff scores for the identification of reading and arithmetic disabilities as in these studies. Similarly Dirks et al. [32] found a higher percentage of combined reading and arithmetic disabilities than the disability in reading or arithmetic alone by using different assessments as in studies of Badian and Lewis et al. And they emphasized that children with combined reading and arithmetic disabilities were different from those who had reading or arithmetic disability alone in terms of cognitive and neuropsychological differences [32].

In 2007, Von Aster et al. [33] performed a study with 337 children, and the reading disorder was found in 3.3%, writing disorder in 5.7%, and mathematics disorder in 1.8%. In the study conducted by Landerl and Moll [34] in 2010 with 2586 children, the reading disorder was found to be prevalent in 2.9%, written expression disorder was 4.1%, and mathematics disorder was 3.2%. A study in France detected prevalence rates of dyslexia between 5.0 and 10.0% in school-age children in the same year [35]. Dhanda and Jagawat [36] worked with 1156 children, and the reading disorder was 22%, written expression disorder was 22%, and mathematics disorder was 16%. After the findings with different results according to the different standard deviations in 2014 by Moll et al. [3], Cappa et al. [37] performed a study in 2015 that reading disorder was found to be 4.75%; Fortes et al., on the other hand, found the cases of prevalence of SLD to be 7.6%, with reading disorder at 7.5%, writing disorder at 5.4%, and mathematics disorder at 6.0% [22]; Gorker et al. determined 3.6% for reading, 6.9% for writing, and 6.5% for mathematics difficulties [7].

The roles of family history and genetic load are considered in reading difficulties and mathematics difficulties, and it is suggested that phonologic problems stated in the etiology of the reading difficulties can create different rates of reading difficulties interculturally, depending on the spoken language. The difficulties in phonemic compliance led to phonologic problems leading to reading difficulties; so, it is suggested that reading difficulties are seen less in countries that have good phoneme-grapheme harmony, and there are higher rates in countries that have poor phoneme-grapheme harmony [27]. For instance, according to the UK Parliamentary Office of Science and Technology, the prevalence of SLD reading disorder in the UK is higher due to differences in pronunciation of a letter in English than most languages and inconsistencies in writing and vocabulary [38].

There are no prevalence studies of mathematic disability that considered longitudinal data, except with 210 sample that were followed multiple times during a 4-year period that found 9.6% by Mazzocco and Myers (2003) [39]. Although large cohort studies do exist with a larger sample initially, a small subset of children is identified as potentially displaying mathematics difficulties, so these studies have not provided a detailed comparison of the cognitive and demographic characteristics of subtypes of learning difficulty. And also two studies investigated the prevalence of specific learning difficulties in arithmetic skills but did not assess their types (e.g., number sense, number facts, and mathematical reasoning) [3, 22]. Different levels of prevalence results of mathematics disability are attributed to some methodological differences of studies. One of them is the method that uses IQ-achievement discrepancy. In retrospective population-based study with 5718

**21**

**Specific learning disorder (%)**

**Reading disorder (%)**

**Written expression disorder (%)**

**Mathematic disorder (%)**

3.6 1.3 6.55

3.9 6.6 5.54–5.98

9.6 2.27–6.59

5.9–13.8

3.4

2.3

**Reading + mathematics disorder (%)**

**Methodology** Questionnaire Standardized tests

Standardized tests

Questionnaire and standardized tests

Standardized tests

Questionnaire Standardized tests

Standardized tests

Standardized tests

Standardized tests

Questionnaire and standardized tests

Questionnaire

Standardized tests

Standardized tests

Standardized tests

Standardized tests

Questionnaire and standardized tests

Standardized tests

Questionnaire

2.2 3.9

Badian [28] Lewis et al. [29]

Gross-Tsur et al. [45]

Miles et al. [30]

Badian [31] Hein et al. [42]

Ramaa and Gowramma [46]

Mazzocco and Myers

[39]

Desoete et al. [43]

Barbaresi et al. [40]

Altarac et al. [4]

Von Aster et al. [33]

Barahmand [41]

Lagae [27] Dirks et al. [32]

Landerl and Moll [34]

Geary [44] Taanila et al. [15]

21.2

3.3 5–17 19.9

2.9

4.1

5.7

1.8 3.76 10.3

3.2 5.4

7.6

9.7

4.19

6

> 20

*The Prevalence and Gender Differences in Specific Learning Disorder*

*DOI: http://dx.doi.org/10.5772/intechopen.90214*


*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

in terms of cognitive and neuropsychological differences [32].

for mathematics difficulties [7].

reading only 6.6%, and for arithmetic only 2.3%. And Lewis reported prevalence proportions as follows: 2.3% for combined reading and arithmetic, 3.9% for reading only, and 1.3% for arithmetic only. When different methods and materials are used in the prevalence studies, different results are obtained as in the studies of Badian and Lewis. While Badian evaluated comprehension in reading, Lewis evaluated word weakness. Although they are both reading processes, they in part require different cognitive skills. Therefore it leads to the identification of a different population of weak readers. Furthermore, another source of variable results across studies is the use of different cutoff scores for the identification of reading and arithmetic disabilities as in these studies. Similarly Dirks et al. [32] found a higher percentage of combined reading and arithmetic disabilities than the disability in reading or arithmetic alone by using different assessments as in studies of Badian and Lewis et al. And they emphasized that children with combined reading and arithmetic disabilities were different from those who had reading or arithmetic disability alone

In 2007, Von Aster et al. [33] performed a study with 337 children, and the reading disorder was found in 3.3%, writing disorder in 5.7%, and mathematics disorder in 1.8%. In the study conducted by Landerl and Moll [34] in 2010 with 2586 children, the reading disorder was found to be prevalent in 2.9%, written expression disorder was 4.1%, and mathematics disorder was 3.2%. A study in France detected prevalence rates of dyslexia between 5.0 and 10.0% in school-age children in the same year [35]. Dhanda and Jagawat [36] worked with 1156 children, and the reading disorder was 22%, written expression disorder was 22%, and mathematics disorder was 16%. After the findings with different results according to the different standard deviations in 2014 by Moll et al. [3], Cappa et al. [37] performed a study in 2015 that reading disorder was found to be 4.75%; Fortes et al., on the other hand, found the cases of prevalence of SLD to be 7.6%, with reading disorder at 7.5%, writing disorder at 5.4%, and mathematics disorder at 6.0% [22]; Gorker et al. determined 3.6% for reading, 6.9% for writing, and 6.5%

The roles of family history and genetic load are considered in reading difficulties and mathematics difficulties, and it is suggested that phonologic problems stated in the etiology of the reading difficulties can create different rates of reading difficulties interculturally, depending on the spoken language. The difficulties in phonemic compliance led to phonologic problems leading to reading difficulties; so, it is suggested that reading difficulties are seen less in countries that have good phoneme-grapheme harmony, and there are higher rates in countries that have poor phoneme-grapheme harmony [27]. For instance, according to the UK Parliamentary Office of Science and Technology, the prevalence of SLD reading disorder in the UK is higher due to differences in pronunciation of a letter in English

than most languages and inconsistencies in writing and vocabulary [38]. There are no prevalence studies of mathematic disability that considered longitudinal data, except with 210 sample that were followed multiple times during a 4-year period that found 9.6% by Mazzocco and Myers (2003) [39]. Although large cohort studies do exist with a larger sample initially, a small subset of children is identified as potentially displaying mathematics difficulties, so these studies have not provided a detailed comparison of the cognitive and demographic characteristics of subtypes of learning difficulty. And also two studies investigated the prevalence of specific learning difficulties in arithmetic skills but did not assess their types (e.g., number sense, number facts, and mathematical reasoning) [3, 22]. Different levels of prevalence results of mathematics disability are attributed to some methodological differences of studies. One of them is the method that uses IQ-achievement discrepancy. In retrospective population-based study with 5718

**20**



*Overview of the prevalence rates of specific learning disorder, reading disorder, written expression disorder, mathematics disorder, and reading-mathematics disorder.*

 **1.**

**23**

*The Prevalence and Gender Differences in Specific Learning Disorder*

children assessed prevalence rates based on different formules and found 5.9% to 13.8% and also significantly more frequent among boys than girls [40]. Barahmand studied 1171 children who are at grades 2–5 and found 3.76% [41]. Others defined mathematics disability by the severity of the mathematics impairment have used performance cutoffs on standardized tests. Some of these studies and their prevalence rates are as follows: 3.6 and 3.9% by Badian's studies [28, 31], 1.3% by study of Lewis et al. [29], 6.6% by study of Hein et al. [42], 9.6% by studies of Mazzocco and Myers [39], 5.9–13.8% by study of Barbaresi et al. [40], 2.27–6.59% by study of Desoete et al. [43], 5.6–10.3% by study of Dirks et al. [32], and 5.4% by study of Geary [44]. The other researchers defined mathematics disability using a 2-year achievement delay as a diagnostic criterion. They found the prevalence rates to be 6.55 [45] and 5.54–5.98% [46]. Recently, Devine et al. compared mathematics and reading difficulties with 1004 primary school children and reported that there were no differences between boys and girls when a discrepancy criterion was applied [47]. The study in 2018 by Morsanyi et al. evaluated the prevalence rates of specific learning disorder in mathematics, gender differences, and comorbid conditions. The prevalence rate was 6%. They found persistent difficulties in reading (5.6%) and language difficulties in English (11.5%) and also found that they had other comorbid symptoms and disorders such as social, emotional, and behavioral difficulties, autism, or attention deficit hyperactivity disorder [8]. There is still no agreed definition of mathematics disability and are controversies between researchers based on cutoff decisions, specificity and gender differences. Prevalence rates

In the prevalence studies of specific learning disorders, ADHD, which receives the most comorbidity and is the most studied disorder, should be considered [1, 48]. Two American national studies by the same researchers found 4% prevalence of comorbidity [17, 49]. DuPaul et al. reported this comorbidity rate as 18–60% and found that the incidence of SLD in ADHD patients was 7 times higher than that of the population [50]. Some clinical studies have reported extremely high prevalence rates of SLD as 70% or ADHD as 82.5% in comorbid cases [51, 52]. Genetic studies support that these two disorders may be associated with similar hereditary factors [53–55]. The high comorbidity between SLD and ADHD, inadequate SLD definitions, and different methods used in studies may have different results in evaluating the prevalence of SLD. And also symptoms of children diagnosed with SLD are more persistent when they have behavioral problems in the first years of school than with SLDs without ADHD or any comorbidity [56]. Therefore, early diagnosis and treatment interven-

tions can significantly change the incidence and prevalence rates of SLD.

DSM-5 is stated that SLD is two to three times more prevalent in boys than in girls [1]. In 4 different epidemiologic studies including 9799 children from England, Wales, and New Zealand, boy/girl rates of reading difficulties were 21.6%/7.9%, 20.6%/9.8%, 17.6%/13.0%, and 18.0%/13.0%. In this study, reading and spelling deficits were not analyzed separately, so that it remained unresolved [12]. Landerl and Moll reported balanced gender ratios for reading (fluency) deficits but a disproportionate number of boys for spelling deficits in German population [34]. In a study of Moll et al., more problems in boys than girls for

**4. Gender differences of specific learning disorder**

*DOI: http://dx.doi.org/10.5772/intechopen.90214*

are summarized in **Table 1**.

**3. Comorbidity of specific learning disorder**

#### *Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

*The Prevalence and Gender Differences in Specific Learning Disorder DOI: http://dx.doi.org/10.5772/intechopen.90214*

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

**22**

**Specific** 

**Reading** 

**Written expression** 

**Mathematic** 

**Reading +**

**mathematics** 

**Methodology**

Questionnaire

Questionnaire

DSM-V criteria 1 standard deviation

DSM-V criteria 1.25 standard deviation

DSM-V criteria 1.5 standard deviation

Questionnaire

DSM-V criteria checklists and questionnaire

Checklists

DSM-V criteria and standardized tests

**disorder (%)**

**disorder (%)**

**disorder (%)**

**disorder (%)**

**learning** 

**disorder (%)**

Dhanda and Jagawat [36]

Al-Yagon et al. [20]

Moll et al. [3]

1.2 6.49 5.14

3.8 4.75

Cappa et al. [37]

Fortes et al. [22]

Gorker et al. [7]

Morsanyi et al. [8]

**Table 1.**

7.6 13.6

3.6 5.6

7.5

5.4 6.9

6 6.5

6 *Overview of the prevalence rates of specific learning disorder, reading disorder, written expression disorder, mathematics disorder, and reading-mathematics disorder.*

5.02

6.67 6.86

4.84 3.31 2.39

22

22

16 children assessed prevalence rates based on different formules and found 5.9% to 13.8% and also significantly more frequent among boys than girls [40]. Barahmand studied 1171 children who are at grades 2–5 and found 3.76% [41]. Others defined mathematics disability by the severity of the mathematics impairment have used performance cutoffs on standardized tests. Some of these studies and their prevalence rates are as follows: 3.6 and 3.9% by Badian's studies [28, 31], 1.3% by study of Lewis et al. [29], 6.6% by study of Hein et al. [42], 9.6% by studies of Mazzocco and Myers [39], 5.9–13.8% by study of Barbaresi et al. [40], 2.27–6.59% by study of Desoete et al. [43], 5.6–10.3% by study of Dirks et al. [32], and 5.4% by study of Geary [44]. The other researchers defined mathematics disability using a 2-year achievement delay as a diagnostic criterion. They found the prevalence rates to be 6.55 [45] and 5.54–5.98% [46]. Recently, Devine et al. compared mathematics and reading difficulties with 1004 primary school children and reported that there were no differences between boys and girls when a discrepancy criterion was applied [47]. The study in 2018 by Morsanyi et al. evaluated the prevalence rates of specific learning disorder in mathematics, gender differences, and comorbid conditions. The prevalence rate was 6%. They found persistent difficulties in reading (5.6%) and language difficulties in English (11.5%) and also found that they had other comorbid symptoms and disorders such as social, emotional, and behavioral difficulties, autism, or attention deficit hyperactivity disorder [8]. There is still no agreed definition of mathematics disability and are controversies between researchers based on cutoff decisions, specificity and gender differences. Prevalence rates are summarized in **Table 1**.

#### **3. Comorbidity of specific learning disorder**

In the prevalence studies of specific learning disorders, ADHD, which receives the most comorbidity and is the most studied disorder, should be considered [1, 48]. Two American national studies by the same researchers found 4% prevalence of comorbidity [17, 49]. DuPaul et al. reported this comorbidity rate as 18–60% and found that the incidence of SLD in ADHD patients was 7 times higher than that of the population [50]. Some clinical studies have reported extremely high prevalence rates of SLD as 70% or ADHD as 82.5% in comorbid cases [51, 52]. Genetic studies support that these two disorders may be associated with similar hereditary factors [53–55]. The high comorbidity between SLD and ADHD, inadequate SLD definitions, and different methods used in studies may have different results in evaluating the prevalence of SLD. And also symptoms of children diagnosed with SLD are more persistent when they have behavioral problems in the first years of school than with SLDs without ADHD or any comorbidity [56]. Therefore, early diagnosis and treatment interventions can significantly change the incidence and prevalence rates of SLD.

#### **4. Gender differences of specific learning disorder**

DSM-5 is stated that SLD is two to three times more prevalent in boys than in girls [1]. In 4 different epidemiologic studies including 9799 children from England, Wales, and New Zealand, boy/girl rates of reading difficulties were 21.6%/7.9%, 20.6%/9.8%, 17.6%/13.0%, and 18.0%/13.0%. In this study, reading and spelling deficits were not analyzed separately, so that it remained unresolved [12]. Landerl and Moll reported balanced gender ratios for reading (fluency) deficits but a disproportionate number of boys for spelling deficits in German population [34]. In a study of Moll et al., more problems in boys than girls for

combined reading and spelling problems were identified, and when isolated spelling disorder was evaluated, gender ratios were found balanced [3]. According to these studies, dyslexia was found to be higher in boys than girls. The most common reported in the literature is that of no gender difference of mathematics disability [8, 29, 39, 42, 43, 45, 47]. The other studies reported higher prevalence of mathematics difficulties in girls [3, 32, 34, 45] or boys [31, 40, 46, 57]. And also some studies reported inconsistency findings. For example, Devine et al. reported that although there was no gender difference in the prevalence of math learning difficulties between boys and girls, mathematics difficulties were much more common for girls than for boys [47].

#### **5. Conclusion**

SLD is a multifactorial disorder which has in its etiology a genetic predisposition and family load, developmental and cognitive factors, language spoken, and environmental factors including the level of education and socioeconomic situation. Comorbidity with other mental disorders reveals more severe symptoms of it. And also if clinical and educational interventions are not performed, behavioral and emotional symptoms may accompany this diagnosis. The use of diagnostic criteria and structured scales, whether the disorder is a uniform or mixed type of disorder, the characteristics of the spoken language, and the assessment of environmental factors will help to determine the prevalence rate results and treatment interventions more specific. An educational approach and early intervention treatment after the awareness of SLD findings will reduce the difficulties that may arise with this disorder in the preschool period.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Author details**

Işık Görker Department of Child and Adolescent Psychiatry, Faculty of Medicine, Trakya University, Edirne, Turkey

\*Address all correspondence to: isikgorker@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**25**

*The Prevalence and Gender Differences in Specific Learning Disorder*

in mathematics and comorbidity with other developmental disorders in primary school-age children. British Journal of Psychology. 2018;**109**(4):917-

940. DOI: 10.1111/bjop.12322

2010;**2**:18-25

pone.0056688

[9] Rathore S, Mangal S, Agdi P, Rathore K, Nema R, Mahatma O. An overview on dyslexia and its treatment. Journal of Global Pharma Technology.

[10] Sun Z, Zou L, Zhang J, Mo S, Shao S, Zhong R, et al. Prevalence and associated risk factors of dyslexic children in a middle-sized city of China: A cross-sectional study. PLoS One. 2013;**8**(2):e56688. DOI: 10.1371/journal.

[11] Vlachos F, Avramidis E, Dedousis G, Chalmpe M, Ntalla I, Giannakopoulou M. Prevalence and gender ratio of dyslexia in Greek adolescents and its association with parental history and brain injury. American Journal of Educational

Research. 2013;**1**(1):22-25

jama.291.16.2007

APA; 2000

[12] Rutter M, Caspi A, Fergusson D, Horwood LJ, Goodman R, Maughan B, et al. Sex differences in developmental reading disability: New findings from 4 epidemiological studies. Journal of the American Medical Association. 2004;**291**(16):2007-2012. DOI: 10.1001/

[13] Alesi M, Rappo G, Pepi A. Selfesteem at school and self-handicapping in childhood: Comparison of groups with learning disabilities. Psychological

[14] Association AP. Diagnostic and Statistical Manual of Mental Disorders 4th edn (DSM-IV). Washington, DC:

[15] Taanila A, Yliherva A, Kaakinen M, Moilanen I, Ebeling H. An epidemiological

Reports. 2012;**111**(3):952-962

*DOI: http://dx.doi.org/10.5772/intechopen.90214*

[1] Association AP. Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM V). Washington DC: American Psychiatric Association; 2013

[2] Tannock R. Rethinking ADHD and LD in DSM-5: Proposed changes in diagnostic criteria. Journal of Learning Disabilities. 2013;**46**(1):5-25. DOI:

10.1177/0022219412464341

[3] Moll K, Kunze S, Neuhoff N, Bruder J, Schulte-Korne G. Specific learning disorder: Prevalence and gender differences. PLoS One.

[4] Altarac M, Saroha E. Lifetime prevalence of learning disability among US children. Pediatrics. 2007;**119**(Supplement 1):S77-S83

[5] Choudhary M, Jain A, Chahar C, Singhal AK. A case control study on specific learning disorders in school going children in Bikaner city. Indian Journal of Pediatrics. 2012;**79**(11):1477- 1481. DOI: 10.1007/s12098-012-0699-7

[6] Fluss J, Ziegler JC, Warszawski J, Ducot B, Richard G, Billard C. Poor reading in French elementary school: The interplay of cognitive, behavioral, and socioeconomic factors. Journal of Developmental and Behavioral Pediatrics. 2009;**30**(3):206-216. DOI: 10.1097/DBP.0b013e3181a7ed6c

[7] Gorker I, Bozatli L, Korkmazlar U, Yucel Karadag M, Ceylan C, Sogut C, et al. The probable prevalence and sociodemographic characteristics of specific learning disorder in primary school children in edirne. Noro Psikiyatri Arsivi. 2017;**54**(4):343-349.

prevalence of specific learning disorder

DOI: 10.5152/npa.2016.18054

[8] Morsanyi K, van Bers B, McCormack T, McGourty J. The

2014;**9**(7):e103537. DOI: 10.1371/journal.

**References**

pone.0103537

*The Prevalence and Gender Differences in Specific Learning Disorder DOI: http://dx.doi.org/10.5772/intechopen.90214*

#### **References**

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

more common for girls than for boys [47].

disorder in the preschool period.

The authors declare no conflict of interest.

\*Address all correspondence to: isikgorker@gmail.com

provided the original work is properly cited.

**Conflict of interest**

**Author details**

University, Edirne, Turkey

Işık Görker

**5. Conclusion**

combined reading and spelling problems were identified, and when isolated spelling disorder was evaluated, gender ratios were found balanced [3]. According to these studies, dyslexia was found to be higher in boys than girls. The most common reported in the literature is that of no gender difference of mathematics disability [8, 29, 39, 42, 43, 45, 47]. The other studies reported higher prevalence of mathematics difficulties in girls [3, 32, 34, 45] or boys [31, 40, 46, 57]. And also some studies reported inconsistency findings. For example, Devine et al. reported that although there was no gender difference in the prevalence of math learning difficulties between boys and girls, mathematics difficulties were much

SLD is a multifactorial disorder which has in its etiology a genetic predisposition and family load, developmental and cognitive factors, language spoken, and environmental factors including the level of education and socioeconomic situation. Comorbidity with other mental disorders reveals more severe symptoms of it. And also if clinical and educational interventions are not performed, behavioral and emotional symptoms may accompany this diagnosis. The use of diagnostic criteria and structured scales, whether the disorder is a uniform or mixed type of disorder, the characteristics of the spoken language, and the assessment of environmental factors will help to determine the prevalence rate results and treatment interventions more specific. An educational approach and early intervention treatment after the awareness of SLD findings will reduce the difficulties that may arise with this

Department of Child and Adolescent Psychiatry, Faculty of Medicine, Trakya

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

**24**

[1] Association AP. Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM V). Washington DC: American Psychiatric Association; 2013

[2] Tannock R. Rethinking ADHD and LD in DSM-5: Proposed changes in diagnostic criteria. Journal of Learning Disabilities. 2013;**46**(1):5-25. DOI: 10.1177/0022219412464341

[3] Moll K, Kunze S, Neuhoff N, Bruder J, Schulte-Korne G. Specific learning disorder: Prevalence and gender differences. PLoS One. 2014;**9**(7):e103537. DOI: 10.1371/journal. pone.0103537

[4] Altarac M, Saroha E. Lifetime prevalence of learning disability among US children. Pediatrics. 2007;**119**(Supplement 1):S77-S83

[5] Choudhary M, Jain A, Chahar C, Singhal AK. A case control study on specific learning disorders in school going children in Bikaner city. Indian Journal of Pediatrics. 2012;**79**(11):1477- 1481. DOI: 10.1007/s12098-012-0699-7

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[8] Morsanyi K, van Bers B, McCormack T, McGourty J. The prevalence of specific learning disorder in mathematics and comorbidity with other developmental disorders in primary school-age children. British Journal of Psychology. 2018;**109**(4):917- 940. DOI: 10.1111/bjop.12322

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[16] Whitsell LJ. Learning disorders as a school health problem—Neurological and psychiatric aspects. California Medicine. 1969;**111**(6):433

[17] Pastor PN, Reuben CA. Attention deficit disorder and learning disability: United States, 1997-98. Vital Health and Statistics. Data from the National Health Interview Survey: ERIC. 2002

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[19] Yao B, Wu HR. Risk factors of learning disabilities in Chinese children in Wuhan. Biomedical and Environmental Sciences. 2003;**16**(4):392-397

[20] Al-Yagon M, Cavendish W, Cornoldi C, Fawcett AJ, Grunke M, Hung LY, et al. The proposed changes for DSM-5 for SLD and ADHD: International perspectives—Australia, Germany, Greece, India, Israel, Italy, Spain, Taiwan, United Kingdom, and United States. Journal of Learning Disabilities. 2013;**46**(1):58-72. DOI: 10.1177/0022219412464353

[21] Del'Homme M, Kim TS, Loo SK, Yang MH, Smalley SL. Familial association and frequency of learning disabilities in ADHD sibling pair families. Journal of Abnormal Child Psychology. 2007;**35**(1):55-62. DOI: 10.1007/s10802-006-9080-5

[22] Fortes IS, Paula CS, Oliveira MC, Bordin IA, de Jesus Mari J, Rohde LA. A cross-sectional study to assess the

prevalence of DSM-5 specific learning disorders in representative school samples from the second to sixth grade in Brazil. European Child & Adolescent Psychiatry. 2016;**25**(2):195-207. DOI: 10.1007/s00787-015-0708-2

[23] Geary DC. Mathematical disabilities: Cognitive, neuropsychological, and genetic components. Psychological Bulletin. 1993;**114**(2):345-362. DOI: 10.1037/0033-2909.114.2.345

[24] Hecht SA, Torgesen JK, Wagner RK, Rashotte CA. The relations between phonological processing abilities and emerging individual differences in mathematical computation skills: A longitudinal study from second to fifth grades. Journal of Experimental Child Psychology. 2001;**79**(2):192-227

[25] Jordon NC, Kaplan D, Hanich LB. Achievement growth in children with learning difficulties in mathematics: Findings of a two-year longitudinal study. Journal of Educational Psychology. 2002;**94**(3):586

[26] Geary DC, Hoard MK. Numerical and arithmetical deficits in learningdisabled children: Relation to dyscalculia and dyslexia. Aphasiology. 2001;**15**(7):635-647

[27] Lagae L. Learning disabilities: Definitions, epidemiology, diagnosis, and intervention strategies. Pediatric Clinics of North America. 2008;**55**(6):1259-1268, vii. DOI: 10.1016/j.pcl.2008.08.001

[28] Badian NA. Dyscalculia and nonverbal disorders of learning. Progress in Learning Disabilities. 1983;**5**:235-264

[29] Lewis C, Hitch GJ, Walker P. The prevalence of specific arithmetic difficulties and specific reading difficulties in 9- to 10-year-old boys and

**27**

*The Prevalence and Gender Differences in Specific Learning Disorder*

screening on specific learning disorders in an Italian speaking high genetic homogeneity area. Research in Developmental Disabilities. 2015;**45-46**:329-342. DOI: 10.1016/j.

[38] Dalton P. Dyslexia & Dyscalculia. Parliamentary Office of Science and Technology. Postnote; 2004:226

defining mathematics learning disability in the primary school-age years. Annals of Dyslexia. 2003;**53**(1):218-253. DOI:

[39] Mazzocco MM, Myers GF. Complexities in identifying and

10.1007/s11881-003-0011-7

[40] Barbaresi WJ, Katusic SK, Colligan RC, Weaver AL,

289. DOI: 10.1367/A04-209R.1

[41] Barahmand U. Arithmetic disabilities: Training in attention and memory enhances arithmetic ability. Research Journal of Biological Sciences.

[42] Hein J, Bzufka MW, Neumärker K-J. The specific disorder of arithmetic skills. Prevalence studies in a rural and an urban population sample and their clinico-neuropsychological validation.

European Child & Adolescent Psychiatry. 2000;**9**(2):S87-S101

[43] Desoete A, Roeyers H, De

10.1177/00222194040370010601

2004;**37**(1):50-61. DOI:

Clercq A. Children with mathematics learning disabilities in Belgium. Journal of Learning Disabilities.

[44] Geary DC. Missouri longitudinal study of mathematical development and disability. BJEP Monograph Series II, Number 7-Understanding Number Development and Difficulties. 31:

2008;**3**(11):1305-1312

Jacobsen SJ. Math learning disorder: Incidence in a population-based birth cohort, 1976-82, Rochester, Minn. Ambulatory Pediatrics. 2005;**5**(5):281-

ridd.2015.07.011

*DOI: http://dx.doi.org/10.5772/intechopen.90214*

girls. Journal of Child Psychology and Psychiatry. 1994;**35**(2):283-292. DOI: 10.1111/j.1469-7610.1994.tb01162.x

[30] Miles T, Haslum M, Wheeler T. Gender ratio in dyslexia. Annals of

[31] Badian NA. Reading disability defined as a discrepancy between listening and reading comprehension: A longitudinal study of stability, gender differences, and prevalence. Journal of Learning Disabilities.

[32] Dirks E, Spyer G, van Lieshout EC, de Sonneville L. Prevalence of combined reading and arithmetic disabilities. Journal of Learning Disabilities. 2008;**41**(5):460-473. DOI: 10.1177/0022219408321128

[33] von Aster M, Schweiter M,

bei Kindern. Zeitschrift für Entwicklungspsychologie und Pädagogische Psychologie.

2007;**39**(2):85-96

encep.2009.02.005

Weinhold Zulauf M. Rechenstörungen

[34] Landerl K, Moll K. Comorbidity of learning disorders: Prevalence and familial transmission. Journal of Child Psychology and Psychiatry. 2010;**51**(3):287-294. DOI: 10.1111/j.1469-7610.2009.02164.x

[35] Huc-Chabrolle M, Barthez MA, Tripi G, Barthelemy C, Bonnet-Brilhault F. Psychocognitive and psychiatric disorders associated with developmental dyslexia: A clinical and scientific issue. Encephale. 2010;**36**(2):172-179. DOI: 10.1016/j.

[36] Dhanda A, Jagawat T. Prevalence and pattern of learning disabilities in school children. Delhi Psychiatry

[37] Cappa C, Giulivi S, Schiliro A, Bastiani L, Muzio C, Meloni F. A

Journal. 2013;**16**(2):386-390

Dyslexia. 1998;**48**(1):27-55

1999;**32**(2):138-148

*The Prevalence and Gender Differences in Specific Learning Disorder DOI: http://dx.doi.org/10.5772/intechopen.90214*

girls. Journal of Child Psychology and Psychiatry. 1994;**35**(2):283-292. DOI: 10.1111/j.1469-7610.1994.tb01162.x

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

prevalence of DSM-5 specific learning disorders in representative school samples from the second to sixth grade in Brazil. European Child & Adolescent Psychiatry. 2016;**25**(2):195-207. DOI:

10.1007/s00787-015-0708-2

[23] Geary DC. Mathematical disabilities: Cognitive,

10.1037/0033-2909.114.2.345

neuropsychological, and genetic components. Psychological

Bulletin. 1993;**114**(2):345-362. DOI:

[24] Hecht SA, Torgesen JK, Wagner RK, Rashotte CA. The relations between phonological processing abilities and emerging individual differences in mathematical computation skills: A longitudinal study from second to fifth grades. Journal of Experimental Child Psychology. 2001;**79**(2):192-227

[25] Jordon NC, Kaplan D, Hanich LB. Achievement growth in children with learning difficulties in mathematics: Findings of a two-year longitudinal study. Journal of Educational Psychology. 2002;**94**(3):586

[26] Geary DC, Hoard MK. Numerical and arithmetical deficits in learningdisabled children: Relation to

dyscalculia and dyslexia. Aphasiology.

[27] Lagae L. Learning disabilities: Definitions, epidemiology, diagnosis,

Pediatric Clinics of North America. 2008;**55**(6):1259-1268, vii. DOI: 10.1016/j.pcl.2008.08.001

[28] Badian NA. Dyscalculia and nonverbal disorders of learning. Progress in Learning Disabilities.

[29] Lewis C, Hitch GJ, Walker P. The prevalence of specific arithmetic difficulties and specific reading

difficulties in 9- to 10-year-old boys and

and intervention strategies.

2001;**15**(7):635-647

1983;**5**:235-264

study on Finnish school-aged children with learning difficulties and behavioural problems. International Journal of Circumpolar Health. 2011;**70**(1):59-71.

[16] Whitsell LJ. Learning disorders as a school health problem—Neurological and psychiatric aspects. California

[17] Pastor PN, Reuben CA. Attention deficit disorder and learning disability: United States, 1997-98. Vital Health and Statistics. Data from the National Health

[18] Silver LB. Developmental learning disorder. In: Lewis M, editor. Child and Adolescent Psychiatry Textbook. 3rd ed. Philadelphia: Lippincott Williams &

DOI: 10.3402/ijch.v70i1.17799

Medicine. 1969;**111**(6):433

Interview Survey: ERIC. 2002

Wilkins; 2002. pp. 621-629

2003;**16**(4):392-397

[19] Yao B, Wu HR. Risk factors of learning disabilities in Chinese children in Wuhan. Biomedical and Environmental Sciences.

[20] Al-Yagon M, Cavendish W, Cornoldi C, Fawcett AJ, Grunke M, Hung LY, et al. The proposed changes for DSM-5 for SLD and ADHD: International perspectives—Australia, Germany, Greece, India, Israel, Italy, Spain, Taiwan, United Kingdom, and United States. Journal of Learning Disabilities. 2013;**46**(1):58-72. DOI:

10.1177/0022219412464353

10.1007/s10802-006-9080-5

[21] Del'Homme M, Kim TS, Loo SK, Yang MH, Smalley SL. Familial association and frequency of learning disabilities in ADHD sibling pair families. Journal of Abnormal Child Psychology. 2007;**35**(1):55-62. DOI:

[22] Fortes IS, Paula CS, Oliveira MC, Bordin IA, de Jesus Mari J, Rohde LA. A cross-sectional study to assess the

**26**

[30] Miles T, Haslum M, Wheeler T. Gender ratio in dyslexia. Annals of Dyslexia. 1998;**48**(1):27-55

[31] Badian NA. Reading disability defined as a discrepancy between listening and reading comprehension: A longitudinal study of stability, gender differences, and prevalence. Journal of Learning Disabilities. 1999;**32**(2):138-148

[32] Dirks E, Spyer G, van Lieshout EC, de Sonneville L. Prevalence of combined reading and arithmetic disabilities. Journal of Learning Disabilities. 2008;**41**(5):460-473. DOI: 10.1177/0022219408321128

[33] von Aster M, Schweiter M, Weinhold Zulauf M. Rechenstörungen bei Kindern. Zeitschrift für Entwicklungspsychologie und Pädagogische Psychologie. 2007;**39**(2):85-96

[34] Landerl K, Moll K. Comorbidity of learning disorders: Prevalence and familial transmission. Journal of Child Psychology and Psychiatry. 2010;**51**(3):287-294. DOI: 10.1111/j.1469-7610.2009.02164.x

[35] Huc-Chabrolle M, Barthez MA, Tripi G, Barthelemy C, Bonnet-Brilhault F. Psychocognitive and psychiatric disorders associated with developmental dyslexia: A clinical and scientific issue. Encephale. 2010;**36**(2):172-179. DOI: 10.1016/j. encep.2009.02.005

[36] Dhanda A, Jagawat T. Prevalence and pattern of learning disabilities in school children. Delhi Psychiatry Journal. 2013;**16**(2):386-390

[37] Cappa C, Giulivi S, Schiliro A, Bastiani L, Muzio C, Meloni F. A

screening on specific learning disorders in an Italian speaking high genetic homogeneity area. Research in Developmental Disabilities. 2015;**45-46**:329-342. DOI: 10.1016/j. ridd.2015.07.011

[38] Dalton P. Dyslexia & Dyscalculia. Parliamentary Office of Science and Technology. Postnote; 2004:226

[39] Mazzocco MM, Myers GF. Complexities in identifying and defining mathematics learning disability in the primary school-age years. Annals of Dyslexia. 2003;**53**(1):218-253. DOI: 10.1007/s11881-003-0011-7

[40] Barbaresi WJ, Katusic SK, Colligan RC, Weaver AL, Jacobsen SJ. Math learning disorder: Incidence in a population-based birth cohort, 1976-82, Rochester, Minn. Ambulatory Pediatrics. 2005;**5**(5):281- 289. DOI: 10.1367/A04-209R.1

[41] Barahmand U. Arithmetic disabilities: Training in attention and memory enhances arithmetic ability. Research Journal of Biological Sciences. 2008;**3**(11):1305-1312

[42] Hein J, Bzufka MW, Neumärker K-J. The specific disorder of arithmetic skills. Prevalence studies in a rural and an urban population sample and their clinico-neuropsychological validation. European Child & Adolescent Psychiatry. 2000;**9**(2):S87-S101

[43] Desoete A, Roeyers H, De Clercq A. Children with mathematics learning disabilities in Belgium. Journal of Learning Disabilities. 2004;**37**(1):50-61. DOI: 10.1177/00222194040370010601

[44] Geary DC. Missouri longitudinal study of mathematical development and disability. BJEP Monograph Series II, Number 7-Understanding Number Development and Difficulties. 31:

British Psychological Society; 2010. pp. 31-49

[45] Gross-Tsur V, Manor O, Shalev RS. Developmental dyscalculia: Prevalence and demographic features. Developmental Medicine and Child Neurology. 1996;**38**(1):25-33. DOI: 10.1111/j.1469-8749.1996.tb15029.x

[46] Ramaa S, Gowramma I. A systematic procedure for identifying and classifying children with dyscalculia among primary school children in India. Dyslexia. 2002;**8**(2):67-85

[47] Devine A, Soltesz F, Nobes A, Goswami U, Szucs D. Gender differences in developmental dyscalculia depend on diagnostic criteria. Learning and Instruction. 2013;**27**:31-39. DOI: 10.1016/j.learninstruc.2013.02.004

[48] Pham AV, Riviere A. Specific learning disorders and ADHD: Current issues in diagnosis across clinical and educational settings. Current Psychiatry Reports. 2015;**17**(6):38. DOI: 10.1007/ s11920-015-0584-y

[49] Pastor PN, Reuben CA. Diagnosed attention deficit hyperactivity disorder and learning disability: United States, 2004-2006. Data from the National Health Interview Survey. Vital and Health Statistics. Series 10, Number 237: ERIC; 2008

[50] DuPaul GJ, Volpe RJ. ADHD and learning disabilities: Research findings and clinical implications. Current Attention Disorders Reports. 2009;**1**(4):152

[51] Altay MA, Gorker I. Assessment of psychiatric comorbidity and WISC-R profiles in cases diagnosed with specific learning disorder according to DSM-5 criteria. Noro Psikiyatri Arsivi. 2018;**55**(2):127-134. DOI: 10.5152/ npa.2017.18123

[52] Mayes SD, Calhoun SL, Crowell EW. Learning disabilities and ADHD: Overlapping spectrum disorders. Journal of Learning Disabilities. 2000;**33**(5):417-424

[53] Cheung CH, Frazier-Wood AC, Asherson P, Rijsdijk F, Kuntsi J. Shared cognitive impairments and aetiology in ADHD symptoms and reading difficulties. PLoS One. 2014;**9**(6):e98590. DOI: 10.1371/journal. pone.0098590

[54] Hong DS. Here/in this issue and there/abstract thinking: Learning disorders and ADHD: Are LDs getting the attention they deserve? Journal of the American Academy of Child and Adolescent Psychiatry. 2014;**53**(9):933

[55] Willcutt EG, Pennington BF, Smith SD, Cardon LR, Gayán J, Knopik VS, et al. Quantitative trait locus for reading disability on chromosome 6p is pleiotropic for attention-deficit/hyperactivity disorder. American Journal of Medical Genetics. 2002;**114**(3):260-268

[56] Sanson A, Prior M, Smart D. Reading disabilities with and without behaviour problems at 7-8 years: Prediction from longitudinal data from infancy to 6 years. Journal of child Psychology and Psychiatry. 1996;**37**(5):529-541

[57] Reigosa-Crespo V, Valdes-Sosa M, Butterworth B, Estevez N, Rodriguez M, Santos E, et al. Basic numerical capacities and prevalence of developmental dyscalculia: The Havana Survey. Developmental Psychology. 2012;**48**(1):123-135. DOI: 10.1037/ a0025356

**29**

disabilities [4].

**Chapter 3**

**Abstract**

Disabilities

*Misciagna Sandro*

anatomical networks, learning systems

assessment and cognitive interventions.

and intellectual disabilities [3].

**1. Cognitive bases of learning disabilities**

Neural Correlates in Learning

In recent years, researchers have done significant advances on the study of learning disabilities in particular in terms of comprehension of cognitive and anatomical mechanisms. The understanding of neural mechanism of learning disabilities is useful for their management and cognitive treatment. The advent of functional neuroimaging methods has also identified anatomical networks and neurological learning systems that have contributed to knowledge of neurobiology of learning deficits. On the other side, neuropsychological assessment, with comprehensive test or specific cognitive tasks, has proved to be useful to analyze specific cognitive deficits to find potential targets of intervention for cognitive compensation. In this chapter the author summarizes major scientific advances in particular in the study of neuroanatomical mechanism based on structural and functional neuroimaging of children with learning disorders, developmental disorders, and language impairment, in particular with dyslexia which is one of the most common learning disabilities.

**Keywords:** learning disabilities, learning deficits, learning disorders, dyslexia, reading disorders, dyscalculia, math disorders, dysgraphia, text generation disorders, anatomical mechanism, neurobiology, neural mechanism, functional neuroimaging,

Learning disabilities have been studied by neuropsychological researchers over

Early cases of children with learning disorders were described by an ophthalmologist who studied children with reading difficulties without brain lesions, so

Subsequently medical researchers used the term "dyslexia" to describe children with troubles in reading and spelling isolated words; they attributed dyslexia to a disorder of cerebral dominance for language [2]. Other authors used the term "learning disabilities" to refer to children with unexpected difficulties secondary to language disorders, differentiating learning disabilities from behavioral disorders

In the 1970s, neuropsychologists started a period of research to identify the cognitive bases of learning disabilities. They emphasized in particular the importance of profile interpretations for inferring brain dysfunction in learning

the past 50 years, so many scientific articles have been published on this topic. The understanding of learning disorders has relevant implications both for

they considered these children as affected by "word blindness" [1].

#### **Chapter 3**

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

and ADHD: Overlapping spectrum disorders. Journal of Learning Disabilities. 2000;**33**(5):417-424

[53] Cheung CH, Frazier-Wood AC, Asherson P, Rijsdijk F, Kuntsi J. Shared cognitive impairments and aetiology in ADHD symptoms and reading difficulties. PLoS One.

2014;**9**(6):e98590. DOI: 10.1371/journal.

[54] Hong DS. Here/in this issue and there/abstract thinking: Learning disorders and ADHD: Are LDs getting the attention they deserve? Journal of the American Academy of Child and Adolescent Psychiatry. 2014;**53**(9):933

[55] Willcutt EG, Pennington BF, Smith SD, Cardon LR, Gayán J, Knopik VS, et al. Quantitative trait locus for reading disability on chromosome 6p is pleiotropic for attention-deficit/hyperactivity disorder. American Journal of Medical Genetics.

[56] Sanson A, Prior M, Smart D. Reading disabilities with and without behaviour problems at 7-8 years: Prediction from longitudinal data from infancy to 6 years. Journal of child Psychology and Psychiatry.

[57] Reigosa-Crespo V, Valdes-Sosa M,

Rodriguez M, Santos E, et al. Basic numerical capacities and prevalence of developmental dyscalculia: The Havana Survey. Developmental Psychology. 2012;**48**(1):123-135. DOI: 10.1037/

2002;**114**(3):260-268

1996;**37**(5):529-541

a0025356

Butterworth B, Estevez N,

pone.0098590

British Psychological Society; 2010.

[45] Gross-Tsur V, Manor O, Shalev RS.

Prevalence and demographic features. Developmental Medicine and Child Neurology. 1996;**38**(1):25-33. DOI: 10.1111/j.1469-8749.1996.tb15029.x

Developmental dyscalculia:

[46] Ramaa S, Gowramma I. A systematic procedure for identifying and classifying children with dyscalculia among primary school children in India.

[47] Devine A, Soltesz F, Nobes A, Goswami U, Szucs D. Gender

[48] Pham AV, Riviere A. Specific learning disorders and ADHD: Current issues in diagnosis across clinical and educational settings. Current Psychiatry Reports. 2015;**17**(6):38. DOI: 10.1007/

[49] Pastor PN, Reuben CA. Diagnosed attention deficit hyperactivity disorder and learning disability: United States, 2004-2006. Data from the National Health Interview Survey. Vital and Health Statistics. Series 10, Number 237:

[50] DuPaul GJ, Volpe RJ. ADHD and learning disabilities: Research findings and clinical implications. Current Attention Disorders Reports.

[51] Altay MA, Gorker I. Assessment of psychiatric comorbidity and WISC-R profiles in cases diagnosed with specific learning disorder according to DSM-5 criteria. Noro Psikiyatri Arsivi. 2018;**55**(2):127-134. DOI: 10.5152/

s11920-015-0584-y

ERIC; 2008

2009;**1**(4):152

npa.2017.18123

[52] Mayes SD, Calhoun SL, Crowell EW. Learning disabilities

differences in developmental dyscalculia depend on diagnostic criteria. Learning and Instruction. 2013;**27**:31-39. DOI: 10.1016/j.learninstruc.2013.02.004

Dyslexia. 2002;**8**(2):67-85

pp. 31-49

**28**

## Neural Correlates in Learning Disabilities

*Misciagna Sandro*

#### **Abstract**

In recent years, researchers have done significant advances on the study of learning disabilities in particular in terms of comprehension of cognitive and anatomical mechanisms. The understanding of neural mechanism of learning disabilities is useful for their management and cognitive treatment. The advent of functional neuroimaging methods has also identified anatomical networks and neurological learning systems that have contributed to knowledge of neurobiology of learning deficits. On the other side, neuropsychological assessment, with comprehensive test or specific cognitive tasks, has proved to be useful to analyze specific cognitive deficits to find potential targets of intervention for cognitive compensation. In this chapter the author summarizes major scientific advances in particular in the study of neuroanatomical mechanism based on structural and functional neuroimaging of children with learning disorders, developmental disorders, and language impairment, in particular with dyslexia which is one of the most common learning disabilities.

**Keywords:** learning disabilities, learning deficits, learning disorders, dyslexia, reading disorders, dyscalculia, math disorders, dysgraphia, text generation disorders, anatomical mechanism, neurobiology, neural mechanism, functional neuroimaging, anatomical networks, learning systems

#### **1. Cognitive bases of learning disabilities**

Learning disabilities have been studied by neuropsychological researchers over the past 50 years, so many scientific articles have been published on this topic.

The understanding of learning disorders has relevant implications both for assessment and cognitive interventions.

Early cases of children with learning disorders were described by an ophthalmologist who studied children with reading difficulties without brain lesions, so they considered these children as affected by "word blindness" [1].

Subsequently medical researchers used the term "dyslexia" to describe children with troubles in reading and spelling isolated words; they attributed dyslexia to a disorder of cerebral dominance for language [2]. Other authors used the term "learning disabilities" to refer to children with unexpected difficulties secondary to language disorders, differentiating learning disabilities from behavioral disorders and intellectual disabilities [3].

In the 1970s, neuropsychologists started a period of research to identify the cognitive bases of learning disabilities. They emphasized in particular the importance of profile interpretations for inferring brain dysfunction in learning disabilities [4].

Other researchers identified neuropsychological correlates of reading difficulties including finger agnosia [5], right–left confusion, auditory–visual integration [6], color-naming difficulties [7], or other language problems.

Some scientists hypothesized that learning disabilities could be related to a parietal lobe disorder [5] or to a developmental Gerstmann syndrome [8].

Some authors attributed reading difficulties to a maturational lag in brain development [9] or to language difficulties [10].

Other researchers criticized theories based on group comparison of single variables in favor of multivariate approaches [11]. This led to researches in which profile of neuropsychological tests were identified to better study the cognitive deficits of learning disabilities [12].

One of the most significance influences on the scientific understanding of learning disabilities was the "theory of speech processing" as a segmented signal of phonological representation [13]. According to this theory, phonological awareness is a metacognitive understanding of the sound structure of speech. The children learning to read must link the orthographic patterns of written language to the internal structure of speech to access the developing lexical system. This theory has been verified across languages that vary in the transparency of orthography and phonology [14].

These discoveries were important in the understanding of learning disabilities since a specific phonological awareness and cognitive skill was considered linked to decoding a specific academic skill, explaining success and failure in reading.

The differentiation of learning disabilities into academic domains produced an expansion of base researches about cognitive correlates and neurobiological factors related to cognitive domains of learning disabilities [15].

Thus learning disorders were separated into three principal domains and six subdomains:


According to Pennington and Peterson, problems in these cognitive domains generate higher-order language, attentional, and executive disorders that affect oral and written language [16]. In other cases, these cognitive disorders are often comorbid with other behavioral traits, such as attention-deficit/hyperactivity disorders (ADHD) [17] or developmental language disorders [18].

Over the years, international researchers have mapped the framework of different sources of variability that influence learning disabilities [19] to help to establish the bases for effective interventions (**Figure 1**).

According to this framework, learning disabilities are related with neurobiological factors (brain structure and function, genetic factors) [15], cognitive processes (e.g., phonemic awareness), psychosocial factors (e.g., attention, anxiety, motivation), and environmental context (socioeconomic conditions, schooling, instruction, home environment).

**31**

functional technologies.

positron emission tomography) [32].

disorder [25].

**Figure 1.**

*Neural Correlates in Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.92294*

*Framework of different sources that influence learning disabilities.*

memory are linked to learning disorders as well as comorbidity with ADHD [21]. Phonological awareness is also a strong predictor of failure or success in reading acquisition [22]. Time reading and spelling assessment could be used in the identification of dyslexia in more transparent languages [23], while vocabulary tasks, listening comprehension, and attention/executive function tasks could be used to study text-level disorders [24]. The learning abilities of individual with dyslexia have been examined using serial reaction time measures, revealing a moderate effect that indicates that automatization of learning is impaired in this

Neuropsychological studies have also suggested neurological and functional distinction between different types of learning: procedural learning system is involved in implicit learning and impaired in individual with specific language impairments [26], while declarative learning system were argued to be relatively intact. Children with dyslexia appear to have difficulty extracting structure from novel sequences in artificial grammar learning paradigms [27] and difficulties in making judgments about grammaticality, confirming that implicit learning processes are involved in dyslexic patients. Prominent difficulties in procedural learning in sequence-based tasks and relative preservation on declarative and nonsequential procedural learning may explain why individuals with learning disabilities have more difficulties in language tasks in which they have to extract and produce sequential information. Math disabilities without reading difficulties are very common as comorbidity in children with learning disabilities [28]. Attention, working memory, and phonological processing are also overlapped with math problem-solving disorders, even if less studied than computational skills [29]. These findings support the view that mathematical abilities involve multiple cognitive processes and that math disorders reflect more generalized cognitive difficulties [30]. Executive functions that affect

In recent years, research on brain structure and cerebral function of children with learning disabilities has taken advantage of new noninvasive structural and

Most studies have been focused on the study of dyslexia using neuroimaging studies (magnetic resonance imaging (MRI)) or functional studies (electroencephalography, event-related potentials, functional magnetic resonance imaging,

self-regulation are relevant for text generation disorders [31].

**2. Neurobiological bases of learning disabilities**

Researchers have showed that intellectual quotient (IQ ) is not predictive of learning disabilities [20], while processing speed deficits and working

**Figure 1.**

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

parietal lobe disorder [5] or to a developmental Gerstmann syndrome [8]. Some authors attributed reading difficulties to a maturational lag in brain

[6], color-naming difficulties [7], or other language problems.

development [9] or to language difficulties [10].

learning disabilities [12].

phonology [14].

subdomains:

Other researchers identified neuropsychological correlates of reading difficulties including finger agnosia [5], right–left confusion, auditory–visual integration

Some scientists hypothesized that learning disabilities could be related to a

Other researchers criticized theories based on group comparison of single variables in favor of multivariate approaches [11]. This led to researches in which profile of neuropsychological tests were identified to better study the cognitive deficits of

One of the most significance influences on the scientific understanding of learning disabilities was the "theory of speech processing" as a segmented signal of phonological representation [13]. According to this theory, phonological awareness is a metacognitive understanding of the sound structure of speech. The children learning to read must link the orthographic patterns of written language to the internal structure of speech to access the developing lexical system. This theory has been verified across languages that vary in the transparency of orthography and

These discoveries were important in the understanding of learning disabilities since a specific phonological awareness and cognitive skill was considered linked to

The differentiation of learning disabilities into academic domains produced an expansion of base researches about cognitive correlates and neurobiological factors

Thus learning disorders were separated into three principal domains and six

1.Oral reading domains that occur at the level of word (*dyslexia*) and the level of

2.Math domains that could be computational (*dyscalculia*) or involve executive

3.Written language domains that could involve basic skills needed for transcription (handwriting and spelling *dysgraphia*) and generating text in essays or

According to Pennington and Peterson, problems in these cognitive domains generate higher-order language, attentional, and executive disorders that affect oral and written language [16]. In other cases, these cognitive disorders are often comorbid with other behavioral traits, such as attention-deficit/hyperactivity disorders

Over the years, international researchers have mapped the framework of different sources of variability that influence learning disabilities [19] to help to establish

According to this framework, learning disabilities are related with neurobiological factors (brain structure and function, genetic factors) [15], cognitive processes (e.g., phonemic awareness), psychosocial factors (e.g., attention, anxiety, motivation), and environmental context (socioeconomic conditions, schooling, instruc-

Researchers have showed that intellectual quotient (IQ ) is not predictive of learning disabilities [20], while processing speed deficits and working

decoding a specific academic skill, explaining success and failure in reading.

related to cognitive domains of learning disabilities [15].

(ADHD) [17] or developmental language disorders [18].

the bases for effective interventions (**Figure 1**).

tion, home environment).

mathematical functions (*math problem-solving disorders*)

text (*reading comprehension disorders*)

stories *(text generation disorders*)

**30**

*Framework of different sources that influence learning disabilities.*

memory are linked to learning disorders as well as comorbidity with ADHD [21]. Phonological awareness is also a strong predictor of failure or success in reading acquisition [22]. Time reading and spelling assessment could be used in the identification of dyslexia in more transparent languages [23], while vocabulary tasks, listening comprehension, and attention/executive function tasks could be used to study text-level disorders [24]. The learning abilities of individual with dyslexia have been examined using serial reaction time measures, revealing a moderate effect that indicates that automatization of learning is impaired in this disorder [25].

Neuropsychological studies have also suggested neurological and functional distinction between different types of learning: procedural learning system is involved in implicit learning and impaired in individual with specific language impairments [26], while declarative learning system were argued to be relatively intact. Children with dyslexia appear to have difficulty extracting structure from novel sequences in artificial grammar learning paradigms [27] and difficulties in making judgments about grammaticality, confirming that implicit learning processes are involved in dyslexic patients. Prominent difficulties in procedural learning in sequence-based tasks and relative preservation on declarative and nonsequential procedural learning may explain why individuals with learning disabilities have more difficulties in language tasks in which they have to extract and produce sequential information.

Math disabilities without reading difficulties are very common as comorbidity in children with learning disabilities [28]. Attention, working memory, and phonological processing are also overlapped with math problem-solving disorders, even if less studied than computational skills [29]. These findings support the view that mathematical abilities involve multiple cognitive processes and that math disorders reflect more generalized cognitive difficulties [30]. Executive functions that affect self-regulation are relevant for text generation disorders [31].

#### **2. Neurobiological bases of learning disabilities**

In recent years, research on brain structure and cerebral function of children with learning disabilities has taken advantage of new noninvasive structural and functional technologies.

Most studies have been focused on the study of dyslexia using neuroimaging studies (magnetic resonance imaging (MRI)) or functional studies (electroencephalography, event-related potentials, functional magnetic resonance imaging, positron emission tomography) [32].

Studies based on functional neuroimaging have identified a network of three regions localized in the left hemisphere mediating word reading:


This network, universal across different languages and orthographies [33], consists of a dorsal and ventral component that operates in parallel, connecting to the inferior frontal gyrus. The dorsal stream is associated with sublexical route to word meaning, consistent with word reading, while the ventral stream is specialized for visual processing of orthographic patterns [34]. The fusiform gyrus is considered an area that mediates word recognition with direct access to semantic regions in inferior temporal regions [35].

Researches based on functional MRI have demonstrated that the development of ventral system is dependent on exposure to print and that in children this system shows reorganization with explicit instructions in reading [36].

Quantitative analyses of MRI have shown reduced volume of the network of pre-scholars before the onset of formal reading instructions [37].

The dorsal and ventral pathways have resulted similar pattern of activation in children with word-level learning disabilities when compared with children developing reading comprehension learning disabilities (RCLD). In contrast the group of children with RCLD showed reduced deactivation of the left angular, left inferior frontal, and left hippocampal and parahippocampal gyri [38]. In other structural studies conducted on adolescent with RCLD, researchers found reduced gray matter in the right frontal regions, explaining their executive function disorders [39].

Functional MRI studies in adults have found that language learning also implicates corticostriatal and hippocampal systems. These structures are connected to each other as well as to the cortex and to other subcortical structures (**Figure 3**).

**33**

*Neural Correlates in Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.92294*

processes related to words [43].

**Figure 3.**

executive deficits [51].

men are less strongly connected in these individuals [49].

activity in children with math learning disabilities [53].

Functional interactions between these regions have been described during learning processes [40]. Consequently, changes in functional neural activity in one of these regions during language learning might reflect a local change of a complex learning network. The frontal cortex and basal ganglia appear to be relevant in learning the phonology and grammar of a language [41]. The hippocampus is also necessary in word learning; in fact, in fMRI studies, the hippocampus results to be activated during the process of learning new vocabularies [42] and during encoding

*Corticostriatal and hippocampal learning networks that influence language learning.*

The ventral striatum (nucleus accumbens) is activated in learning novel words [44], while the dorsal striatum responds to feedback in verbal paired-associated tasks [45]. Abnormalities in the striatum have been seen also in children with language disorders [46]. Some studies suggest a reduction of volume of the caudate nucleus in children with specific language and learning impairment [47], while others have reported increases in caudate nucleus volume [48]. Functional studies conducted on adults with dyslexia show hyperactivation of the striatum, not seen in children with dyslexia, suggesting to be a compensatory mechanism in adulthood. Structural network analysis in children with a higher risk for dyslexia and other reading difficulties have showed that the hippocampus, temporal lobe, and puta-

Studies conducted on children with math disabilities have found disorders of

Researchers have not found consistent structural differences across all studies in dyslexic patients, probably since this disorder is the result of a combination of multiple risk factors including motor, oral language, phonological disorders, and

Functional neuroimaging studies on numerical processing and mental arithmetic have also demonstrated the existence of a neural network [52], connecting frontotemporal regions with three left parietal circuits: superior parietal, intraparietal, and inferior parietal (**Figure 4**). This network is characterized by increased

Other reports have demonstrated that specific cerebellar regions contribute to cognitive functions in children with learning disorders in particular with verbal

connectivity in temporoparietal and inferior parietal white matter [50].

**Figure 2.** *Cerebral network that influences word reading.*

#### **Figure 3.**

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

regions localized in the left hemisphere mediating word reading:

1.A sublexical dorsal stream localized in temporoparietal areas

2.A lexical ventral stream localized in occipitotemporal region

by temporoparietal or occipitotemporal regions (**Figure 2**)

shows reorganization with explicit instructions in reading [36].

pre-scholars before the onset of formal reading instructions [37].

inferior temporal regions [35].

Studies based on functional neuroimaging have identified a network of three

3.A cerebral area in the left inferior frontal lobe underactivated or overactivated

This network, universal across different languages and orthographies [33], consists of a dorsal and ventral component that operates in parallel, connecting to the inferior frontal gyrus. The dorsal stream is associated with sublexical route to word meaning, consistent with word reading, while the ventral stream is specialized for visual processing of orthographic patterns [34]. The fusiform gyrus is considered an area that mediates word recognition with direct access to semantic regions in

Researches based on functional MRI have demonstrated that the development of ventral system is dependent on exposure to print and that in children this system

Quantitative analyses of MRI have shown reduced volume of the network of

The dorsal and ventral pathways have resulted similar pattern of activation in children with word-level learning disabilities when compared with children developing reading comprehension learning disabilities (RCLD). In contrast the group of children with RCLD showed reduced deactivation of the left angular, left inferior frontal, and left hippocampal and parahippocampal gyri [38]. In other structural studies conducted on adolescent with RCLD, researchers found reduced gray matter in the right frontal regions, explaining their executive function disorders [39]. Functional MRI studies in adults have found that language learning also implicates corticostriatal and hippocampal systems. These structures are connected to each other as well as to the cortex and to other subcortical structures (**Figure 3**).

**32**

**Figure 2.**

*Cerebral network that influences word reading.*

Functional interactions between these regions have been described during learning processes [40]. Consequently, changes in functional neural activity in one of these regions during language learning might reflect a local change of a complex learning network. The frontal cortex and basal ganglia appear to be relevant in learning the phonology and grammar of a language [41]. The hippocampus is also necessary in word learning; in fact, in fMRI studies, the hippocampus results to be activated during the process of learning new vocabularies [42] and during encoding processes related to words [43].

The ventral striatum (nucleus accumbens) is activated in learning novel words [44], while the dorsal striatum responds to feedback in verbal paired-associated tasks [45]. Abnormalities in the striatum have been seen also in children with language disorders [46]. Some studies suggest a reduction of volume of the caudate nucleus in children with specific language and learning impairment [47], while others have reported increases in caudate nucleus volume [48]. Functional studies conducted on adults with dyslexia show hyperactivation of the striatum, not seen in children with dyslexia, suggesting to be a compensatory mechanism in adulthood. Structural network analysis in children with a higher risk for dyslexia and other reading difficulties have showed that the hippocampus, temporal lobe, and putamen are less strongly connected in these individuals [49].

Studies conducted on children with math disabilities have found disorders of connectivity in temporoparietal and inferior parietal white matter [50].

Researchers have not found consistent structural differences across all studies in dyslexic patients, probably since this disorder is the result of a combination of multiple risk factors including motor, oral language, phonological disorders, and executive deficits [51].

Functional neuroimaging studies on numerical processing and mental arithmetic have also demonstrated the existence of a neural network [52], connecting frontotemporal regions with three left parietal circuits: superior parietal, intraparietal, and inferior parietal (**Figure 4**). This network is characterized by increased activity in children with math learning disabilities [53].

Other reports have demonstrated that specific cerebellar regions contribute to cognitive functions in children with learning disorders in particular with verbal

short-term memory deficits [54], reading development [55], or in general to cognitive, emotional, and behavioral functions [56].

According to the cerebellar deficit hypothesis, specific regions of the cerebellum are functionally connected with cerebral reading network [57].

The reading-related cerebral regions that result to have functional connectivity with the cerebellum are supposed to be three: the inferior frontal junction (IFJ), the inferior parietal lobule (IPL), and the middle temporal gyrus (MTG) (**Figure 5**).

**Figure 4.** *Cerebral network that influences numerical processing.*

**35**

**Table 1.**

Numerical processing and mental

*Cerebral areas that influence cognitive learning processes.*

arithmetic

*Neural Correlates in Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.92294*

nology for the third set of connections [55].

cerebral networks that can explain learning disorders.

**3. Conclusions**

**Table 1**).

aspects.

An analysis on connectivity has demonstrated three distinct sets of connections between cerebral and cerebellar regions. The first set of connections consist of a connection between IFJ and IPL that converges to a region in the right lateral posterior inferior cerebellum and is supposed to have a phonological role. The second set of connections consist of a connection between IFJ and MTG, which converges to a region in the right posterior superior cerebellum and is supposed to have a semantic role. The third set consist of a functional connectivity between MTG region and lateral anterior region of the cerebellum. There is not a common functional termi-

Studies conducted on children with learning disabilities, in particular with dyslexia, have shown an involvement in the function of cerebral areas and systems relevant in cognitive process about speech and learning (summarized in

As evidenced in **Table 1**, structural or functional abnormalities of cerebral systems, localized in particular in the left hemisphere, in corticostriatal systems, and in cerebro-cerebellar connections, support the hypothesis of the existence of

These cerebral areas have an important impact on the development of learning and different aspects of language such as phonological and morpho-syntactic

**Cognitive function Cerebral areas Hemisphere**

Executive functions Frontal regions Left and right

Fronto-temporoparietal regions Left

General language learning Corticostriatal and hippocampal systems Left Learning of phonology and grammar Frontal cortex and basal ganglia Left Word learning Hippocampus Left Learning of new words Ventral striatum (nucleus accumbens) Left Feedback in verbal paired-associated tasks Dorsal striatum Left

Math learning Fronto-temporoparietal regions Left Verbal short-term memory Cerebellum Right? Reading development Cerebellum Right?

Word reading Dorsal stream: temporoparietal Left Visual processing of orthographic patterns Ventral stream: occipitotemporal Left Lexical functions Occipitotemporal Left Orthographic function Inferior frontal gyrus Left Word recognition Fusiform gyrus Left Semantic functions Inferior temporal regions Left Reading comprehension Both dorsal and ventral streams Left

**Figure 5.** *Cerebro-cerebellar network that influences reading processing.*

#### *Neural Correlates in Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.92294*

An analysis on connectivity has demonstrated three distinct sets of connections between cerebral and cerebellar regions. The first set of connections consist of a connection between IFJ and IPL that converges to a region in the right lateral posterior inferior cerebellum and is supposed to have a phonological role. The second set of connections consist of a connection between IFJ and MTG, which converges to a region in the right posterior superior cerebellum and is supposed to have a semantic role. The third set consist of a functional connectivity between MTG region and lateral anterior region of the cerebellum. There is not a common functional terminology for the third set of connections [55].

### **3. Conclusions**

*Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

are functionally connected with cerebral reading network [57].

tive, emotional, and behavioral functions [56].

short-term memory deficits [54], reading development [55], or in general to cogni-

According to the cerebellar deficit hypothesis, specific regions of the cerebellum

The reading-related cerebral regions that result to have functional connectivity with the cerebellum are supposed to be three: the inferior frontal junction (IFJ), the inferior parietal lobule (IPL), and the middle temporal gyrus (MTG) (**Figure 5**).

**34**

**Figure 5.**

**Figure 4.**

*Cerebral network that influences numerical processing.*

*Cerebro-cerebellar network that influences reading processing.*

Studies conducted on children with learning disabilities, in particular with dyslexia, have shown an involvement in the function of cerebral areas and systems relevant in cognitive process about speech and learning (summarized in **Table 1**).

As evidenced in **Table 1**, structural or functional abnormalities of cerebral systems, localized in particular in the left hemisphere, in corticostriatal systems, and in cerebro-cerebellar connections, support the hypothesis of the existence of cerebral networks that can explain learning disorders.

These cerebral areas have an important impact on the development of learning and different aspects of language such as phonological and morpho-syntactic aspects.


#### **Table 1.**

*Cerebral areas that influence cognitive learning processes.*

#### *Learning Disabilities - Neurological Bases, Clinical Features and Strategies of Intervention*

However, there is a need to develop further longitudinal studies, conducted on children with learning disabilities, to explore cerebral anatomical and functional alterations during development and their correlation with specific pattern of learning disabilities.

Further progress in understanding the nature and specific components of learning difficulties in children will allow us to develop future specific targets and rehabilitative strategies of intervention.

#### **Author details**

Misciagna Sandro Belcolle Hospital, Viterbo, Italy

\*Address all correspondence to: sandromisciagna@yahoo.it

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**37**

*Neural Correlates in Learning Disabilities DOI: http://dx.doi.org/10.5772/intechopen.92294*

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[11] Doehring DG. The tangled web of behavioral research on developmental dyslexia. In: Benton AL, Pearl D, editors. Dyslexia. New York: Oxford University

[12] Rourke BP, editor. Neuropsychology of Learning Disabilities: Essentials of Subtype Analysis. New York: Guilford

[13] Liberman IY. Basic research in speech and lateralization of language.

[14] Ziegler JC, Goswami U. Reading acquisition, developmental dyslexia, and skilled reading across languages: A psycho-linguistic grain size theory. Psychological Bulletin. 2005;**131**:3-29

[15] Fletcher JM, Grinorenko EL. Neuropsychology of learning disabilities: The past and the future. Journal of the International Neuropsychological Society. 2017;**23**(9-10):930-940

[16] Pennington BF, Peterson R. Neurodevelopmental disorders: Learning disorders. In: Tasman A, Kay J, Lieberman JA, First MB, Riba MR, editors. Psychiatry. 4th ed. Chichester,

UK: John Wiley & Sons; 2015

[17] Mahone M, Denckla MB. Attention-deficit/hyperactivity disorder. Journal of the International Neuropsychological Association.

[18] Pennington BF. Diagnosing

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2017;**23**(9-10):916-929

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New York: Guilford; 2009

Bulletin of the Orton Society.

Press; 1978. pp. 123-137

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However, there is a need to develop further longitudinal studies, conducted on children with learning disabilities, to explore cerebral anatomical and functional alterations during development and their correlation with specific pattern of learn-

Further progress in understanding the nature and specific components of learning difficulties in children will allow us to develop future specific targets and

**36**

**Author details**

ing disabilities.

rehabilitative strategies of intervention.

Misciagna Sandro

Belcolle Hospital, Viterbo, Italy

provided the original work is properly cited.

\*Address all correspondence to: sandromisciagna@yahoo.it

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

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**41**

Section 2

Differential Diagnosis

of Common Learning

Disabilities

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Section 2
