**3. Profile of cognitive functions in Duchenne muscular dystrophy**

Duchenne muscular dystrophy (DMD) is a genetic disease of the muscles caused by deficits in the dystrophin-glycoprotein complex (DGC). The loss of dystrophin is associated with a complex set of physiological and anatomical adaptations that are known contributors to the cognitive deficits observed in patients with DMD and related disorders. Some studies have indicated disordered CNS architecture, abnormalities in dendrites, and loss of neurons in boys with DMD [5]. These boys show EEG abnormalities [5], and the prevalence of epilepsy is higher in DMD (6.3%) than the general population [6]. Studies of CT [7] and MRI [8] have indicated brain atrophy in patients with DMD. These studies suggest that functional and morphological abnormalities are affected by the absence of dystrophins.

Several studies have assessed the intellectual functioning of boys with DMD and reported mean IQs that are approximately one standard deviation lower than the general population [9–12]. Also, boys with DMD have lower verbal IQs (VIQ ) than performance IQs (PIQ ) [10, 13–16]. Furthermore, Hinton et al. [17] indicated that boys with DMD did poorly on Story Recall, Digit Span, and Auditory Comprehension compared to unaffected siblings. They concluded that verbal working memory was impaired selectively. Moreover, sequential processing ability is more impaired than simultaneous processing ability in boys with DMD [14, 18].

**37**

*Cognitive Function and Quality of Life of Muscular Dystrophy*

delineate age-related cognitive changes in DMD populations [19].

Cotton [19] reported that the boys with DMD had a mean full-scale IQ (FIQ ) and a PIQ score of approximately 80 based on a meta-analysis of 1224 boys with DMD. However, the mean VIQ scores improved with age, particularly in the verbal subscales: Information, Similarities, Arithmetic, Comprehension, and Digit Span. Moreover, there were less deficits in older age groups in abilities of logical verbal abstract reasoning, language development, and arithmetic. They suggested the need to adopt more specific and directed neuropsychological assessments to further

Ueda et al. [20] conducted a study using a wide range of neuropsychological assessment instruments to investigate whether the cognitive weaknesses remain in

Fifteen inpatients and outpatients with DMD (mean age = 30.4 years, age range = 19–44 years) participated in the study. Twenty-four subscales of the Wechsler Adult Intelligence Scale-III (WAIS-III), the Clinical Assessment for Attention (CAT) [21], and the Wechsler Memory Scale (WMS-R) were used for the

• Ten WAIS-III subscales: (1) Picture Completion, (2) Vocabulary, (3) Similarities, (4) Arithmetic, (5) Matrix Reasoning, (6) Information, (7) Comprehension, (8)

Modalities, (13) Memory Updating (3 span), (14) Memory Updating (4 span), (15) Paced Auditory Serial Addition Test (PASAT; 2 sec.), (16) PASAT (1 sec.),

Association, (20) Verbal Paired Associate, (21) Figural Memory, (22) Delayed Logical Memory, (23) Delayed Visual Paired Association, and (24) Delayed

All assessment instruments were standardized for use in Japan. Therefore, the Z test was used to compare the scores of DMD patients on the 24 subscales with the

On the CAT, they were significantly deficient in all subscales (**Figure 2**): Symbol Digit Modalities (M = 42.5, SD = 12.5), Auditory Detection (M = 84.2, SD = 18.8), Memory Updating 3 span (M = 79.2, SD = 25.9), Memory Updating (4 span) (M = 51.4, SD = 30.4), PASAT (2 sec.) (M = 37.2, SD = 30.5), PASAT(1 sec.)

(M = 17.4, SD = 16.1), and Position Stroop (M = 97.1, SD = 3.3). In addition, the total Response Time for Position Stroop of patients group (M = 163.0, SD = 75.5) was

Symbol Search, (9) Letter-Number Sequencing, and (10) Digit Span

• Seven subscales of CAT: (11) Auditory Detection, (12) Symbol Digit

• Seven subscales of WMS-R: (18) Logical Memory, (19) Visual Paired

The mean and SD of WAIS-III in DMD adults patients (**Figure 1**), Picture Completion (M = 6.20, SD = 2.86), Arithmetic (M = 5.80, SD = 1.97), Matrix Reasoning (M = 7.47, SD = 3.74), Symbol Search (M = 6.20, SD = 3.84), Letter-Number Sequencing (M = 6.97, SD = 4.64), and Digit Span (M = 7.33, SD = 2.23) were significantly deficient (p < . 01) compared to the normal population (M = 10, SD = 3). However, there were no significant differences in Vocabulary (M = 8.80, SD = 3.28), Similarities (M = 8.80, SD = 4.31), Information (M = 8.93, SD = 3.08), and Comprehension (M = 9.33, SD = 4.61). The mean FIQ of adult patients with DMD was 87.4 (SD = 15.96, range = 61–109), which was estimated by dyadic short forms of WAIS-III [22, 23].

*DOI: http://dx.doi.org/10.5772/intechopen.86222*

**3.1 Cognitive functions in adults with DMD**

assessment. The assessment instruments were:

and (17) Position Stroop

Verbal Paired Associates

significantly longer than the normal population.

normal population.

adult patients with DMD.

*Muscular Dystrophies*

must live in recuperation wards.

dystrophy [2] and reported that all the sampled patients were living at home. The QOL was assessed by the Sickness Impact Scale (SIP) and the Psychosocial Well-Being Questionnaire, which indicated that their disability and dependence on others increased, whereas ADL decreased during the previous 5 years. Moreover, the patients' QOL and life satisfaction also decreased. Boström and Ahlström investigated 46 people with muscular dystrophy through interviews using a qualitative research approach for 10 years [3]. They reported that nearly all muscular dystrophy patients had decreasing functions such as limited mobility, increasing fatigue, and feebleness, accompanied by psychological distress. Moreover, if there is a difficulty in securing assistance for patients to continue living in their homes, they

Ueda et al. [4] investigated the QOL of 50 inpatients with muscular dystrophy. The QOL was assessed by the World Health Organization-Quality of Life 26 (WHO-26). Results indicated that the mean QOL score (SD) of patients with muscular dystrophy was 2.96 (0.34), which was significantly lower than the general Japanese population (mean 3.75) or patients with cancer (mean 3.3). The results of the comparison between patients' conditions indicated that those who could move by using a wheelchair had higher QOL scores than those who were bedridden. The QOL score of patients that had throat surgery was higher than those who had no surgery. The comparison between clinical types indicated that the QOL in myotonic dystrophy was significantly lower than limb girdle-type muscular dystrophy or Fukuyama-type congenital muscular dystrophy. They also investigated factors that

could affect the QOL of patients with muscular dystrophy, including age,

in activities. The results of categorical regression analysis (R2

gender, clinical type, duration of the diseases, throat surgery, duration from throat surgery, functional independence (Barthel Index), use of a ventilator, use of a wheelchair, use of a computer, the frequency of family visits, and participation

F = 2.479, P < 0.05) showed that only the use of a computer influenced the QOL (β = 0.598). These results suggest that using a computer could be an effective method of maintaining or improving the QOL of muscular dystrophy inpatients, with deteriorated body functions and limited activities due to the progression of the disease.

**3. Profile of cognitive functions in Duchenne muscular dystrophy**

logical abnormalities are affected by the absence of dystrophins.

Duchenne muscular dystrophy (DMD) is a genetic disease of the muscles caused by deficits in the dystrophin-glycoprotein complex (DGC). The loss of dystrophin is associated with a complex set of physiological and anatomical adaptations that are known contributors to the cognitive deficits observed in patients with DMD and related disorders. Some studies have indicated disordered CNS architecture, abnormalities in dendrites, and loss of neurons in boys with DMD [5]. These boys show EEG abnormalities [5], and the prevalence of epilepsy is higher in DMD (6.3%) than the general population [6]. Studies of CT [7] and MRI [8] have indicated brain atrophy in patients with DMD. These studies suggest that functional and morpho-

Several studies have assessed the intellectual functioning of boys with DMD and reported mean IQs that are approximately one standard deviation lower than the general population [9–12]. Also, boys with DMD have lower verbal IQs (VIQ ) than performance IQs (PIQ ) [10, 13–16]. Furthermore, Hinton et al. [17] indicated that boys with DMD did poorly on Story Recall, Digit Span, and Auditory Comprehension compared to unaffected siblings. They concluded that verbal working memory was impaired selectively. Moreover, sequential processing ability is more impaired than simultaneous processing ability in boys with DMD [14, 18].

= 0.671, R2

= 0.400,

**36**

Cotton [19] reported that the boys with DMD had a mean full-scale IQ (FIQ ) and a PIQ score of approximately 80 based on a meta-analysis of 1224 boys with DMD. However, the mean VIQ scores improved with age, particularly in the verbal subscales: Information, Similarities, Arithmetic, Comprehension, and Digit Span. Moreover, there were less deficits in older age groups in abilities of logical verbal abstract reasoning, language development, and arithmetic. They suggested the need to adopt more specific and directed neuropsychological assessments to further delineate age-related cognitive changes in DMD populations [19].
