**3. Mild cognitive impairment and dementia**

In cognitive aging, there is a decline which is considered normal. Some cognitive functions remain stable while others decline as part of normal aging. These cognitive changes associated with age occur to people who do not have pathologies that affect memory or cognitive abilities, and these changes do not interfere with the ability to participate in everyday activities. However, cognitive changes in aging can have a wide range, from those that are normal to those that are pathological, and between these there may be a series of intermediate changes. This transition state is known as Mild Cognitive Impairment (MCI) [31].

The construct of Mild Cognitive Impairment (MCI) has been extensively used worldwide, both in clinical and in research settings, to define the gray area between intact cognitive functioning and clinical. The MCI intends to identify this intermediate stage of cognitive impairment that is often, but not always, a transitional phase from cognitive changes in normal aging to those typically found in dementia [32]; in this sense, MCI is considered a predemential syndrome [33].

Some of the tasks that have been considered as executive functions are the working memory, the majority of everyday cognitive tasks that require the establishment of goals, the implementation and follow-up of the operations to reach those goals, and both the checkup of each one of these operations and of the fulfillment of the final purpose; their relevance could be used as evidence of the importance of executive functions in the lives of people [25]. In normal aging, it has been found that changes in executive functions are mainly observed in: working memory, when keeping information available for a short period of time; in inhibition, because over the years, more problems to concentrate on relevant information are experienced and inhibit attention to irrelevant aspects, in addition inhibitory processes are less efficient to allow the

initial entry of information into the operational memory and in mental flexibility [26].

and working memory but not the rest of this kind of functions [29].

**3. Mild cognitive impairment and dementia**

care and executive functioning.

148 Gerontology

change related to a pathology.

Processing speed has been defined as the reaction time that produces a global effect on cognition [27]. It is one of the functions in which a decline has been found as part of normal aging, and it has even been associated with the cause of cognitive changes in other domains such as

Moreover, as a cognitive task becomes more complex, older adults may not have the necessary resources of mental operations to carry out the later phases of it because cognitive functioning is slower and sometimes does not allow them to complete some mental operations that are needed for a correct final task performance [28]. Other studies compared two groups, one of young adults and other of older adults, and applied neuropsychological tasks to measure executive functioning and found a lower performance in inhibitory control, abstraction,

The subjective perception of adults about their cognitive functioning (also called meta-memory) is another factor that significantly influences the activities of daily living (ADL) during aging, a recent study showed that a third of the evaluated population reported memory problems, thinking skills, and their ability to reason, all of them associated with their overall health [30]. Finally, it is important to note that the cognitive changes that occur in normal aging are presented as a slight decline and do not interfere with the level of independence during aging; if these changes appear in the opposite way, it is possible to suspect deterioration or cognitive

In cognitive aging, there is a decline which is considered normal. Some cognitive functions remain stable while others decline as part of normal aging. These cognitive changes associated with age occur to people who do not have pathologies that affect memory or cognitive abilities, and these changes do not interfere with the ability to participate in everyday activities. However, cognitive changes in aging can have a wide range, from those that are normal to those that are pathological, and between these there may be a series of intermediate

The construct of Mild Cognitive Impairment (MCI) has been extensively used worldwide, both in clinical and in research settings, to define the gray area between intact cognitive

changes. This transition state is known as Mild Cognitive Impairment (MCI) [31].

In 2013, the American Psychiatric Association (APA) proposed new criteria for dementia in the fifth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5) and recognizes the predementia stage of cognitive impairment [34]. The condition, which has many of the features of MCI, is known as mild neurocognitive disorder (NCD). Mild NCD recognizes subtle features of cognitive impairment that are different from aging but do not represent dementia. Furthermore, mild NCD focuses on the initial phases of cognitive disorders and precedes major NCD that is analogous to the previous diagnosis of dementia.

There are several subtypes of MCI, which differ according to the type and number of impaired cognitive abilities, the most common is the amnesic which mainly involves memory problems, while in the nonamnesic, memory operation is not compromised. Likewise, when only one dimension of cognitive functioning is affected, it is called DCL of a domain or multidomain if more than one cognitive ability (e.g., memory, reasoning, executive functions, etc.) is affected [32]. These MCI subtypes are usually related to different pathological processes, for example, it has been found that people with amnestic DCL are more likely to progress to Alzheimer's disease (AD) [35, 36], while people with nonamnestic MCI are more likely to develop Lewy Body Dementia [36].

According to this definition, MCI is operationalized based on clinical data of changes in cognitive abilities (see **Table 1**). The subjective cognitive complaint needs to be confirmed by objective cognitive measures, such as neuropsychological test batteries. Objective cognitive impairment is defined as a poor performance in one or more cognitive measures, which suggests deficits in one or more cognitive areas or domains. There is no gold standard to specify which neuropsychological test battery to use, but it is important that all the main cognitive areas are examined. Typically, executive functions, attention, language, memory, and visuospatial skills are taken into account. Functional abilities are investigated by means of a thorough interview with the person and with the next of kin and registered in terms of activities of daily living (ADL) and instrumental activities of daily living (IADL) scales [32].

According to this definition, MCI is operationalized based on clinical data of changes in cognitive abilities (see **Table 1**). The subjective cognitive complaint needs to be confirmed by objective cognitive measures, such as neuropsychological test batteries. Objective cognitive impairment is defined as a poor performance in one or more cognitive measures, which suggests deficits in one or more cognitive areas or domains. There is no gold standard to specify which neuropsychological test battery to use, but it is important that all the main cognitive areas are examined. Typically, executive functions, attention, language, memory, and visuospatial skills are taken into account. Functional abilities are investigated by means of an in-depth interview with the person and with the person's next of kin and registered in terms of both activities of daily living (ADL) and instrumental activities of daily living (IADL) scales [32].

It has been shown that a significant proportion of people with MCI progresses to dementia in periods of 1–2 years and approximately 50% progresses toward dementia over a 5-year period [37].


enough to interfere with independence and daily life [34]. However, not all the care professionals and organizations are likely to use the new term. Currently, the Alzheimer's Association, for example, uses the term *dementia* instead of *neurocognitive disorder*. See criteria in **Table 1**. Globally, around 47 million people have dementia, with nearly 60% living in low- and middleincome countries, and there are 9.9 million new cases every year; Alzheimer's disease is the most common cause of dementia and may contribute to 60–70% of cases. The estimated proportion of the general population aged 60 years and over with dementia at a given time is between 5 and 8 per 100 people. The total number of people with dementia is projected to near 75 million in 2030 and almost triple by 2050 to 132 million. Much of this increase is attributable to the rising numbers of people with dementia living in low- and middle-income countries [39]. The most common forms of dementia are Alzheimer's disease and vascular dementia (VD) [40]. **Table 1** shows a comparison of diagnostic criteria in normal aging, mild cognitive impairment, and dementia.

Science has gradually shown which risk factors (RF) for MCI and dementia can be currently considered. The knowledge of RF for these pathological processes plays an important role in its prevention. Ideally, prevention strategies should target people who are not even symptom-

In the health sciences field, a RF is the probability of suffering a certain disease, having a complication or dying [44]. In this paper, we will present some of the most recognized RF, classifying them according to their origin in social, biological, and psychological and by their

Regarding blood pressure (BP), both high and low BP have been linked to cognitive impairment and dementia [45]. The role of cerebral blood vessels in the wide spectrum of pathologies underlying cognitive impairment highlights the importance of vascular structure and function in brain health [46]. The pathophysiology of the relationship between BP and cognition

**Risk factors Modifiable Nonmodifiables**

Genetic Brain injuries

Cognitive Aging

151

http://dx.doi.org/10.5772/intechopen.71551

Age Sex

Metabolic disorders: diabetes mellitus

(B) Psychological Depression —

Intellectual commitment

**4. Risk factors for mild cognitive impairment and dementia**

atic [42]. Prevention of dementia is a public health priority [43].

nature in modifiable and nonmodifiable (see **Table 2**).

**4.1. Biological factors**

*4.1.1. Vascular disorders*

(A) Biological Vascular disorders

(C) Social Education

**Table 2.** Risk factors for MCI and dementia.

**Table 1.** Comparison of the different diagnostic criteria in normal aging, mild cognitive impairment and dementia (according to DSM-IV and DSM-5).

Dementia is a NCD that usually begins gradually and has a progressive course. It can be variable, and there is often a long period of time between the occurrence of the first signs of cognitive impairment and the moment they meet the criteria for the dementia diagnosis [38].

The American Psychiatric Association (APA) introduced in 2013 the term "Major neurocognitive disorder" replacing the term "dementia," defined as a decline in mental ability severe enough to interfere with independence and daily life [34]. However, not all the care professionals and organizations are likely to use the new term. Currently, the Alzheimer's Association, for example, uses the term *dementia* instead of *neurocognitive disorder*. See criteria in **Table 1**.

Globally, around 47 million people have dementia, with nearly 60% living in low- and middleincome countries, and there are 9.9 million new cases every year; Alzheimer's disease is the most common cause of dementia and may contribute to 60–70% of cases. The estimated proportion of the general population aged 60 years and over with dementia at a given time is between 5 and 8 per 100 people. The total number of people with dementia is projected to near 75 million in 2030 and almost triple by 2050 to 132 million. Much of this increase is attributable to the rising numbers of people with dementia living in low- and middle-income countries [39]. The most common forms of dementia are Alzheimer's disease and vascular dementia (VD) [40]. **Table 1** shows a comparison of diagnostic criteria in normal aging, mild cognitive impairment, and dementia.
