Investigation of Poor Academic Achievement in Children with Duchenne Muscular Dystrophy

Dmd mdx mice have defective oligodendrogenesis, delayed myelin compaction and persistent hypomyelination

Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene, resulting in the loss of dystrophin, a large cytosolic protein that links the cytoskeleton to extracellular matrix receptors in skeletal muscle. Aside from progressive muscle damage, many patients with DMD also have neurological deficits of unknown etiology. To investigate potential mechanisms for DMD neurological deficits, we assessed postnatal oligodendrogenesis and myelination in the Dmdmdx mouse model. In the ventricular-subventricular zone (V-SVZ) stem cell niche, we found that oligodendrocyte progenitor cell (OPC) production was deficient, with reduced OPC densities and proliferation, despite a normal stem cell niche organization. In the Dmdmdx corpus callosum, a large white matter tract adjacent to the V-SVZ, we also observed reduced OPC proliferation and fewer oligodendrocytes. Transmission electron microscopy further revealed significantly thinner myelin, an increased number of abnormal myelin structures and delayed myelin compaction, with hypomyelination persisting into adulthood. Our findings reveal alterations in oligodendrocyte development and myelination that support the hypothesis that changes in diffusion tensor imaging seen in patients with DMD reflect developmental changes in myelin architecture.

Neurocognitive functioning among children and young people with Duchenne Muscular Dystrophy: A systematic review and meta-analysis

Objective: The neurocognitive aspects of DMD have received less attention than the physiological sequalae. This study conducted a systematic review and meta-analysis of available literature on the neurocognitive profile of children and young people with DMD. Method: Five databases (EMBASE, Medline, PsycInfo, Scopus and Web of Science) and the grey literature was searched on 27th January 2023. Eligible articles were available in English and reported neurocognitive outcomes. Neurocognitive domains reported in a comparable way across a minimum of three studies were included. The neurocognitive domains of Full-Scale IQ (FSIQ), Verbal IQ (VIQ), Performance IQ (PIQ) and Working memory (WMI) derived from Wechsler scales and receptive vocabulary ability derived from the Peabody Picture Verbal Test (PPVT) were included. A single mean meta-analysis was completed. Results: Relevant data was extracted and presented for 38 eligible studies; 2 of which are from grey literature. Results suggest children with DMD perform around 1SD below non-clinical norms for FSIQ, PIQ, VIQ and WMI. Unlike VIQ, scores derived from the PPVT were within the non-clinical norms. Studies were of moderate - high quality, there was significant heterogeneity and no publication bias. Conclusion: A systematic review of working memory has not previously been completed, it appears that children with DMD perform around 1SD below the mean, like FSIQ, PIQVIQ and WMI. The PPVT is a measure of receptive verbal ability and caution is recommended around the interchangeability of PPVT scores and the wider construct of verbal intelligence.

Computerized working memory training in males with Duchenne muscular dystrophy: A single case experimental design study

Learning disabilities (LDs) and working memory problems (WM) are common brain-related comorbidities in Duchenne muscular dystrophy (DMD). Despite growing evidence on the efficacy of computerized WM training in children with LDs, research in DMD is lacking. This exploratory study assessed whether training (1) improves dystrophin-associated WM problems in DMD, (2) effects are present at post-intervention, 3 and 8 months follow-up, and (3) improves problems that arise from their LDs. A single case non-concurrent multiple baseline across patients design evaluated the target behaviour i.e. parental reports of WM problems of four DMD participants with LDs. Additionally, participants completed cognitive tests of verbal and visual WM, academics, attention, processing speed and fluid reasoning. Parents and teachers completed behavioural questionnaires. Testing and questionnaires were administered at baseline, post-intervention (T2), 3 (T3) and 8 (T4) months follow-up. Positive effects on target behaviour were found for three of four participants, but parental bias cannot be ruled out. Short and long-term, near-and far transfer effects were found for verbal and visual WM (T2:n = 2, T3&T4:n = 1), reading (T2:n = 4,T3:n = 3,T4:n = 2), arithmetic (all T:n = 1), processing speed (all T:n = 4) and fluid reasoning (T2:n = 1,T3&T4:n = 2). Behavioural questionnaires displayed minimal changes (T2:n = 1,T3&T4:n = 2). Promising WM training results are shown in DMD that merit further research.

Effects of the COVID-19 Pandemic on Access to Education and Social Participation in Children and Adolescents with Duchenne Muscular Dystrophy in Switzerland

BACKGROUND

 Two-thirds of patients with Duchenne muscular dystrophy (DMD) have cognitive and neuropsychiatric problems. Concerning their quality of life, negative factors are the lack of qualifying education and social participation in sporting and leisure activities. Adapted assistance in education and participation in social life are thus important. During the coronavirus disease 2019 (COVID-19) pandemic, the pediatric population was less severely impacted by the disease, but by the restrictions associated.

AIM

 The aim of this study was to evaluate the impact of the COVID-19 pandemic regarding access to education and social participation for young patients with DMD in Switzerland.

METHODS

 We conducted a survey study from May to August 2021 assessing the impact of the COVID-19 pandemic on access to education and social participation in 8 to 18 years old patients with DMD in Switzerland.

RESULTS

 Of 60 sent surveys, 40 were returned and included. Mean age of participants was 13.5 years (±3.1 standard deviation); 23/40 of the participants were wheelchair bound, 21/40 attended a special school, and 19/40 a regular school. Of the 22/40 participants receiving assistance at school, 7/40 reported a change caused by the pandemic: for 5/7, the assistance was paused. Of the 12 boys and adolescents attending sporting activities, 10 had to suspend these. Nine attended other leisure activities; for 3/9, these activities were paused.

CONCLUSION

 The COVID-19 pandemic had direct effects on school assistance, sporting, and leisure activities in young patients with DMD in Switzerland. It is important to ensure that school assistance and leisure activities are rapidly resumed.

Longitudinal data of neuropsychological profile in a cohort of Duchenne muscular dystrophy boys without cognitive impairment

The aim of the study was to re-assess neuropsychological profile in a group of boys with Duchenne muscular dystrophy without intellectual disability and neuropsychiatric disorder three years apart from a previous evaluation, to establish possible changes over time. We were also interested in defining more in detail correlation between genotype and neuropsychological phenotype. Thirty-three of the previous 40 subjects (mean age at follow up: 10 years and 7 months) agreed to participate in the follow up study and to perform the new assessment. The results confirm a typical neuropsychological profile, with difficulty in the manipulation of stored information, poor abstract reasoning and planning capacity and impulsiveness, supporting the involvement of a cerebellar striatal cortical network for these children. The more detailed description of subgroups of subjects, according to the real expression of Dp140, let to reveal possible genotype-neuropsychological phenotype correlations, and a more general neuropsychological impairment emerged in boys without Dp140 expression.

Longitudinal Evaluation of Working Memory in Duchenne Muscular Dystrophy

Objective: The developmental maturation of forward and backward digit spans—indices of working memory—in boys with nonsense (nm) Duchenne muscular dystrophy (DMD) (nmDMD) was assessed using prospective, longitudinal data. Methods: Fifty-five boys of the 57 subjects with genetically confirmed nmDMD—who were from the placebo arm of a 48-week-long phase 2b clinical trial—were evaluated. Forward and backward digit spans were obtained every 12 weeks for a total of five assessments in all study subjects. Changes in forward and backward digit spans were evaluated based on age, corticosteroid treatment, and DMD mutation location. Results: Boys with nmDMD had lower mean scores on normalized forward digit span. Normalized forward digit spans were comparable between subjects stratified by age and between corticosteroid-naïve and corticosteroid-treated subjects. When stratified by DMD mutation location, normalized forward digit spans were lower in nmDMD subjects with mutations downstream of DMD exon 30, exon 45, and exon 63, both at baseline evaluation and at follow-up evaluation at 48 weeks. On average, normalized backward digit span scores were stable over 48 weeks in these subjects. Developmental growth modeling showed that subjects with nmDMD mutations upstream of DMD exon 30, upstream of DMD exon 45, and upstream of DMD exon 63 appeared to make better gains in working memory than subjects with mutations downstream of DMD exon 30, downstream of DMD exon 45, and downstream of DMD exon 63. Conclusion: Performance in working memory shows deficits in nmDMD and differed based on nmDMD location. Maturation in cognition was seen over a 48-week period. The developmental trajectory of working memory in this cohort was influenced by DMD mutation location.

Longitudinal follow-up of verbal span and processing speed in Duchenne muscular dystrophy

Neurocognitive deficits are frequently described in Duchenne muscular dystrophy (DMD), but it is unknown how these progress over time. Our aim was to longitudinally assess verbal span capacity and information processing speed in DMD and to explore a genotype-phenotype relation. Verbal span and processing speed scores were available of 28 males with DMD on two time-points, with a mean time interval of 28.34 months (SD = 16.09). The cohort contained of six patients missing only dystrophin isoform Dp427, sixteen missing Dp427 and Dp140, and six were undeterminable. A lower verbal span capacity was found at the first and second assessment, whereas processing speed was normal at both time-points. Post-hoc analyses suggested lower scores on verbal span and processing speed for patients missing Dp427 and Dp140. In DMD, a developmental stagnation in verbal span capacity, irrespective of normal processing speed, is detected through longitudinal follow-up. This appears more pronounced in patients missing Dp427 and Dp140.

Neurodevelopmental, behavioral, and emotional symptoms common in Duchenne muscular dystrophy

INTRODUCTION

We studied neurodevelopmental and behavioral/emotional symptoms in patients with Duchenne muscular dystrophy (DMD).

METHODS

Retrospective case series of neurodevelopmental and behavioral/emotional symptoms obtained through review of systems of 700 DMD patients in relation to dystrophin gene mutations.

RESULTS

The most common symptoms encountered were emotional/behavioral dysregulation (38.7%), inattention/hyperactive features (31.4%), obsessive and compulsive features (25.0%), and language/speech delays (24.4%). Most patients (72.7%) had at least one symptom. Patients with mutations near the 3' end of the dystrophin gene were at higher risk for developing inattention/hyperactive features, language/speech delays, and global intellectual delays. Those with mutations between exon 31 and 79 had higher risk of clustering of symptoms when compared with those upstream of exon 30.

DISCUSSION

Neurodevelopmental, emotional, and behavioral symptoms are common comorbidities in DMD. There is higher prevalence of inattention/hyperactive features, language/speech delays, and global intellectual delays in genotypes affecting the 3' end of the dystrophin gene.

Instruments for the Assessment of Behavioral and Psychosocial Functioning in Duchenne and Becker Muscular Dystrophy; a Systematic Review of the Literature

Objective

This systematic review aims to provide an overview of instruments used to assess behavioral and psychosocial functioning of patients with Duchenne and Becker muscular dystrophy, as well as to review the psychometric properties and applicability of these instruments.

Methods

Five databases (Embase, Psyc.info, ERIC, Pubmed/Medline, and Cochrane) were searched from inception to June, 2018. Potential articles were rated by two independent reviewers. A predefined PROSPERO form (CRD42017074518) was used to extract data from included articles.

Results

Sixty-one instruments were used in 54 studies. The Child Behavior Checklist is commonly used, but it lacks disease specific psychometric information. Sixteen instruments that contained disease specific psychometric information were included for final evaluation. The results displayed three instruments that are potentially valid for screening of psychosocial problems: The Psychosocial Adjustment and Role Skills Scale 3rd edition, the Pediatric Quality of Life Inventory Generic module, and the Life Satisfaction Index for Adolescents with Duchenne muscular dystrophy. Appropriate instruments for screening of behavioral problems may be: the Strengths and Difficulties Questionnaire, the Generalized Anxiety Disorder-7 item questionnaire, and the Patient Health Questionnaire-9 item questionnaire.

Conclusions

Further research on psychometric properties of screening instruments is crucial to ascertain a gold standard for clinical and research purposes. Meanwhile, for definite diagnostics purposes we recommend a multimethod, multisource, multisetting assessment in this high-risk population.

Advances in imaging of brain abnormalities in neuromuscular disease

Brain atrophy, white matter abnormalities, and ventricular enlargement have been described in different neuromuscular diseases (NMDs). We aimed to provide a comprehensive overview of the substantial advancement of brain imaging in neuromuscular diseases by consulting the main libraries (Pubmed, Scopus and Google Scholar) including the more common forms of muscular dystrophies such as dystrophinopathies, dystroglycanopathies, myotonic dystrophies, facioscapulohumeral dystrophy, limb-girdle muscular dystrophy, congenital myotonia, and congenital myopathies. A consistent, widespread cortical and subcortical involvement of grey and white matter was found. Abnormalities in the functional connectivity in brain networks and metabolic alterations were observed with positron emission tomography (PET) and single photon emission computed tomography (SPECT). Pathological brain changes with cognitive dysfunction seemed to be frequently associated in NMDs. In particular, in congenital muscular dystrophies (CMDs), skeletal muscular weakness, severe hypotonia, WM abnormalities, ventricular dilatation and abnormalities in cerebral gyration were observed.

In dystroglycanopathy 2I subtype (LGMD2I), adult patients showed subcortical atrophy and a WM periventricular involvement, moderate ventriculomegaly, and enlargement of subarachnoid spaces. Correlations with clinical features have been observed with brain imaging characteristics and alterations were prominent in congenital or childhood onset cases. In myotonic dystrophy type 2 (DM2) symptoms seem to be less severe than in type 1 (DM1).

In Duchenne and Becker muscular dystrophies (DMD, BMD) cortical atrophy is associated with minimal ventricular dilatation and WM abnormalities.

Late-onset glycogenosis type II (GSD II) or Pompe infantile forms are characterized by delayed myelination. Only in a few cases of oculopharyngeal muscular dystrophy (OPMD) central nervous system involvement has been described and associated with executive functions impairment.

Executive Functioning in the Dystrophinopathies and the Relation to Underlying Mutation Position

OBJECTIVES

The aim of this study was to investigate executive skills in children with dystrophinopathy and to examine the association between executive functions and dystrophin gene mutation position.

METHODS

Fifty boys with dystrophinopathy (mean age, 11 years 0 months; ages range, 5 to 17 years) completed measures of intellectual functioning (IF), working memory and executive functioning [including Digit Span (working memory) and measures from the NIH Toolbox (selective attention/inhibitory control, set shifting, working memory, and processing speed)]. Parents completed the Behavior Rating Inventory of Executive Function (BRIEF). Mutation positions were categorized into three groups (upstream exon 30, 31-62, and downstream exon 63). Paired-samples t tests compared performance on executive measures to IF, and a one-way (three-group) multivariate analysis of covariance compared cognitive performance with mutation location controlling for motor functioning.

RESULTS

Mean performance on all executive measures was significantly lower than IF. Parents were also more likely to rate their child with dystrophinopathy as having clinically significant executive difficulties on the Shift, Emotional Control, and Behavior Regulation indices of the BRIEF. Mutation analyses resulted in small groups limiting power to detect subtle differences. Those with a downstream mutation position had significantly poorer performance on IF and Total Digit Span, but not on other measures of executive function including behavior.

CONCLUSIONS

Individuals with dystrophinopathy have executive skill deficits, but they are not generally associated with more distal mutations. (JINS, 2019, 25, 146-155).

Neurodevelopmental Needs in Young Boys with Duchenne Muscular Dystrophy (DMD): Observations from the Cooperative International Neuromuscular Research Group (CINRG) DMD Natural History Study (DNHS)

INTRODUCTION

Duchenne muscular dystrophy (DMD) is the most common X-linked neuromuscular condition manifested by progressive skeletal muscle weakness, cardiopulmonary involvement and cognitive deficits. Neurodevelopmental symptoms and signs are under-appreciated in this population despite the recognition that cognition has a major impact on quality-of-life. We describe the neurodevelopmental needs in a large cohort of young boys with DMD from the DMD Natural History Study (DNHS). We explore the association between neurodevelopmental needs and DMD mutation location, and with glucocorticoid use.   Methods: We prospectively evaluated 204 participants between ages 4 to less than 9 years of age with DMD as part of a large, longitudinal, international DNHS. We obtained parent- or primary care-giver report of neurodevelopmental needs as part of their study visit. We assessed the relationship between parent/care-giver neurodevelopmental needs and DMD mutation location, and glucocorticoid use.

RESULTS

The neurodevelopmental needs that were most commonly reported included speech delay (33%), mild developmental delay (24%), significant behavioral problems (16.5%), language impairment (14.5%), learning disability (14.5%), attention-deficit hyperactivity disorder (5%) and autism spectrum disorder (3%). Neurodevelopmental needs were more commonly reported by care-givers in those with DMD mutations downstream of exon 51. There was no relationship between care-giver reported neurodevelopmental needs and glucocorticoid use.

CONCLUSION

Neurodevelopmental needs are highly prevalent in young boys with DMD. Care-givers report higher neurodevelopmental needs when subjects have DMD mutations downstream of exon 51. Early interventions aimed at cognitive health are critical to improve the quality-of-life of individuals with DMD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00468832.

Executive Skills and Academic Achievement in the Dystrophinopathies

OBJECTIVES

To examine academic performance in dystrophinopathy as a function of dystrophin gene mutation position as well as intellectual function, executive skills, socioeconomic status (SES), behavior, and physical ability.

METHODS

In a cross-sectional study, boys with dystrophinopathy (ages 5-17; n=50) completed tests of academics (Woodcock-Johnson-III: spelling, reading, calculation and total scores), executive functioning (selective attention/inhibitory control, set shifting, working memory, and processing speed), single word comprehension and nonverbal reasoning. Motor skills were assessed and parents provided demographic information and child behavioral assessments. Dystrophin gene mutation positions were dichotomized into groups (upstream versus downstream of exon 43, location of isoforms previously linked to intellectual impairment). Genetic mutation groups were compared on measures of academic achievement, and multiple regression analyses examined unique and joint contributions of executive skills, intelligence quotient (IQ), SES, motor abilities, behavior, and mutation positions to academic outcomes.

RESULTS

Academic performance was slightly, yet significantly, lower than IQ and varied as a function of dystrophin gene position, wherein boys possessing the downstream mutation exhibited greater impairment than boys with the upstream mutation. Digit span forward (indexing verbal span), but no other measure of executive function, contributed significant variance to total academic achievement, spelling and calculation.

CONCLUSIONS

Weak academic performance is associated with dystrophinopathy and is more common in downstream mutations. A specific deficit in verbal span may underlie inefficiencies observed in children with dystrophinopathy and may drive deficits impacting academic abilities. (JINS, 2018, 24, 928-938).

Brain-related comorbidities in boys and men with Duchenne Muscular Dystrophy: A descriptive study

AIM

Duchenne Muscular Dystrophy (DMD) is more than a muscle disease since there is a higher prevalence of neuropsychological comorbidities. Similarly, the prevalence of epilepsy is increased. Given the nowadays-increasing interest in brain-related comorbidities in DMD, this study aimed to evaluate the relationship between DMD, epilepsy, and associated neurodevelopmental disorders in an international sample of DMD patients.

METHOD

Using a questionnaire-based study we investigated the occurrence of self/by-proxy reported brain-related comorbidities in a group of 228 DMD patients. We evaluated the presence of epilepsy and other brain-related comorbidities, but also the specific mutation in the dystrophin gene. With respect to epilepsy, all individually reported epilepsy cases as based on the questionnaire results including information provided on epilepsy treatment, EEG abnormalities, and a description of how a typical seizure would look like, were independently and blindly re-assessed by two external paediatric neurologists (Cohen's kappa of 0.85).

RESULTS

Based on the latter, 18 (7.9%) DMD patients were considered to have epilepsy. In patients with both DMD and epilepsy, certain other brain-related comorbidities (i.e. attention deficit hyperactivity disorder, obsessive compulsive disorder, anxiety disorders and sleep disorders) were significantly more prevalent.

CONCLUSION

This study is supportive of a high occurrence of epilepsy and other brain-related comorbidities in DMD. Furthermore this study shows for the first time that the frequency of some of these disorders appear to be further increased when epilepsy is present next to DMD. As this study is limited by the self/by proxy setup and the lack of response rates, future studies should elucidate the true incidence of the (triangular) cooccurrence between epilepsy, neurodevelopmental deficits, and DMD.

Cognitive profile in Duchenne muscular dystrophy boys without intellectual disability: The role of executive functions

The aim of our prospective observational study was to assess profiles of cognitive function and a possible impairment of executive functions in a cohort of boys with Duchenne muscular dystrophy without intellectual and behavior disability. Forty Duchenne boys (range of age: 6 years to 11 years and 6 months) were assessed by Wechsler Intelligence scale and battery of tests including tasks assessing working memory and executive functions (inhibition and switching, problem solving and planning). In our cohort some aspects of cognitive function were often impaired. These included multitasking, problem solving, inhibition and working memory necessary to plan and direct goal oriented behavior. Our results support the suggestion that aspects of cognitive function could be impaired even in boys without intellectual disability and support the hypothesis that executive functions may play an important role in specific aspects of cognitive impairment in Duchenne muscular dystrophy.

Maternal alcohol consumption during pregnancy and child's cognitive performance at 6-8 years of age in rural Burkina Faso: an observational study

Background

In Burkina Faso, it is not uncommon for mothers to drink alcohol, even during pregnancy. We aimed to study the association between maternal alcohol consumption during pregnancy and the child’s cognitive performance using the Kaufman Assessment Battery for Children, 2nd edition (KABC-II) and the Children’s Category Test Level 1 (CCT-1) in rural Burkina Faso.

Methods

We conducted a follow-up study of a community cluster-randomised Exclusive breastfeeding trial, and re-enrolled the children in rural Burkina Faso. A total of 518 children (268 boys and 250 girls) aged 6–8 years were assessed using the KABC-II and the CCT-1. We examined the effect size difference using Cohen’s d and conducted a linear regression analysis to examine the association.

Results

Self-reported alcohol consumption during pregnancy was 18.5% (96/518). Children whose mothers reported alcohol consumption during pregnancy performed significantly poorly for memory and spatial abilities tests from small effect size difference for ‘Atlantis’ (0.27) and ‘Triangle’ (0.29) to moderate effect size difference for ‘Number recall’ (0.72) compared to children whose mothers did not consume alcohol during pregnancy; the exposed children scored significantly higher errors with a small effect size (0.37) at problem solving (CCT-1) test compared to unexposed children.

At unstandardized and standardized multivariable analysis, children whose mothers reported alcohol consumption during pregnancy performed significantly poorer for memory-‘Atlantis’ (p = 0.03) and ‘Number recall’ (p = 0.0001), and spatial ability tests-‘Triangle’ (p = 0.03); they scored significantly higher errors at problem solving CCT-1 test (p = 0.002); all the results were adjusted for age, sex, schooling, stunting, father’s education, mother’s employment and the promotion of exclusive breastfeeding. No statistical association was found for visual abilities-‘Conceptual Thinking’, ‘Face recognition’, ‘Story completion’, and reasoning tests-‘Rover’, ‘Block counting’, and ‘Pattern Reasoning’.

Conclusion

Maternal alcohol consumption during pregnancy is associated with poorer cognitive performance for memory, spatial ability, and problem solving tests in the offspring in rural Burkina Faso. Futures studies needs to assess in more detail the maternal alcohol consumption patterns in Burkina Faso and possible preventive strategies.

Mismatch Negativity Recording in Children With Duchenne Muscular Dystrophy: A Preliminary Study Integrating Neurophysiological and Neuropsychological Results

Many studies on Duchenne muscular dystrophy children support the hypothesis of a specific neuropsychological phenotype affecting mostly phonological skills. This prospective study aimed to shed light on the role of phonological abilities. Fourteen Duchenne muscular dystrophy children and 7 healthy children underwent mismatch negativity. Moreover, verbal intelligence, visuospatial attention, immediate verbal memory, working memory, grammar, vocabulary, visuomotor skills, reading, text comprehension, writing, and arithmetic were tested in Duchenne muscular dystrophy children. No significant difference between control and Duchenne muscular dystrophy children was found neither for mismatch negativity amplitude (P = .191 and .116, respectively) nor for latency (P = .135). Eight (57.14%) patients showed an impairment of immediate verbal memory and of visuomotor skills, 7 (63.64%) patients had a deficit in writing and arithmetic skills, even with a mean normal intelligence quotient. Taken together, the results put in evidence a heterogeneous neuropsychological profile not explainable on the basis of a phonological deficit.

[Central manifestations of dystrophinopathies]

The dystrophin gene involved in Duchenne and Becker muscular dystrophy is expressed in three main tissues resulting in clinical manifestations: skeletal muscle, heart and central nervous system. The 6 different existing dystrophins in the brain may play a role in the maturation and plasticity of neuronal synapses in particular by their functions in clustering and stabilization of different receptors at the post synaptic membrane. The possibility of an intellectual deficiency in Duchenne muscular dystrophy is known from the original description by Duchenne himself. Current data are in line with a constant cognitive impairment with a Gaussian curve shifted intellectual quotient (IQ) at -1 standard deviation from the standard population with an average IQ around 80. Clinical manifestations suggestive of a central nervous system involvement can affect all dystrophinopathies, including isolated central presentations without myopathic sign. The phenotypic spectrum appears broader and more subtle than non specific intellectual deficiency. The isolated or shared involvement of specific cognitive functions is possible (memory functions, executive functions, attention) with or without intellectual deficiency. Autism spectrum disorders are also among the encountered events. In clinical practice, it seems worth to ask for a measurement of serum creatine kinase (CK) in these different situations, keeping in mind that pure forms of central dystrophinopathies with a normal CK level have been recently reported.

Reversal of neurobehavioral social deficits in dystrophic mice using inhibitors of phosphodiesterases PDE5A and PDE9A

Duchenne muscular dystrophy is caused by mutations in the DYSTROPHIN gene. Although primarily associated with muscle wasting, a significant portion of patients (approximately 25%) are also diagnosed with autism spectrum disorder. We describe social behavioral deficits in dystrophin-deficient mice and present evidence of cerebellar deficits in cGMP production. We demonstrate therapeutic potential for selective inhibitors of the cGMP-specific PDE5A and PDE9A enzymes to restore social behaviors in dystrophin-deficient mice.

Digit Span Performance in Children with Dystrophinopathy: A Verbal Span or Working Memory Contribution?

OBJECTIVES

In a large cohort of boys with dystrophinopathies and their unaffected siblings, we examined whether consistently observed performance on digit span is due primarily to a verbal span or executive deficit. We additionally assessed whether digit span performance contributed to the observed variability in reading performance noted in this population.

METHODS

Performance of 170 boys with dystrophinopathy was compared to 95 unaffected sibling controls on measures of verbal function, reading, and digit span. Maximum digit span forward (DSF) and backward (DSB) lengths were converted to Z-scores using normative data. Independent sample t tests, analysis of variance, and hierarchical multiple regression were run (α=0.05).

RESULTS

Probands performed worse than controls on digit span, even after accounting for differences in general verbal function (p<.0001). Differences were significant for both DSF (p<.005) and DSB (p<.0001) span length, and an interaction effect yielded significantly worse DSB compared with DSF (p=.01). Reading performance was also lower in probands (p<.0001). The contribution of general level of verbal function, and forward and backward span lengths, did not vary between groups.

CONCLUSIONS

In boys with dystrophinopathy, decreased performance on digit span appears to be due to both decreased span forward (measuring verbal span only) and backward (measuring verbal span and working memory). The extent to which sibling controls exhibited better performance compared to the probands was significantly greater for backward span when compared with forward span. Thus, immediate verbal memory and executive control are differentially compromised among boys with dystrophinopathy, and both of these abilities independently contribute to reading performance. (JINS, 2016, 22, 777-784).

Diffusion tensor imaging study in Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is a progressive muscle disorder associated with an intellectual deficit which is non-progressive. The aim of this study was to investigate brain microstructural changes in DMD and to explore the relationship between such changes and cognitive impairment.

METHODS

All participants (12 DMD patients, 14 age-matched healthy boys), intelligence quotients (IQs) [both full (FIQ) and verbal (VIQ)] were evaluated using the Wechsler intelligence scale for children China revised (WISC-CR) edition, and brain gray matter (GM) and white matter (WM) changes were mapped using diffusion tensor imaging (DTI) with fractional anisotropy (FA). The differences between groups were analyzed using the t-test and the association of cognition with neuroimaging parameters was evaluated using Pearson's correlation coefficient.

RESULTS

Compared to the normal controls, the DMD group had lower FIQ (82.0±15.39 vs. 120.21±16.06) and significantly lower splenium of corpus callosum (CC) FA values (P<0.05). Splenium of CC FA was positively correlated with VIQ (r=0.588, P=0.044).

CONCLUSIONS

There were microstructural changes of splenium of CC in DMD patients, which was associated with cognitive impairment.

Cognitive and Neurobehavioral Profile in Boys With Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is a progressive neuromuscular condition that has a high rate of cognitive and learning disabilities as well as neurobehavioral disorders, some of which have been associated with disruption of dystrophin isoforms. Retrospective cohort of 59 boys investigated the cognitive and neurobehavioral profile of boys with Duchenne muscular dystrophy. Full-scale IQ of < 70 was seen in 27%; learning disability in 44%, intellectual disability in 19%; attention-deficit/hyperactivity disorder in 32%; autism spectrum disorders in 15%; and anxiety in 27%. Mutations affecting Dp260 isoform and 5'untranslated region of Dp140 were observed in 60% with learning disability, 50% intellectual disability, 77% with autism spectrum disorders, and 94% with anxiety. No statistically significant correlation was noted between comorbidities and dystrophin isoforms; however, there is a trend of cumulative loss of dystrophin isoforms with declining full-scale IQ. Enhanced psychology testing to include both cognitive and neurobehavioral disorders is recommended for all individuals with Duchenne muscular dystrophy.

Reading impairment in Duchenne muscular dystrophy: A pilot study to investigate similarities and differences with developmental dyslexia

Below-average reading performances have been reported in individuals with Duchenne muscular dystrophy (DMD), but literacy problems in these subjects have yet to be characterized. In this study, the presence and characteristics of literacy deficits in boys with DMD were investigated through a comparison with typically developing children and with children affected by developmental dyslexia, with the aim of clarifying whether DMD and developmental dyslexia have overlapping profiles of literacy deficits and whether these deficits are associated, as in children with dyslexia, with impairments in phonological processing and rapid lexical access. The results confirmed the high incidence of literacy problems in boys with DMD and revealed a profile less severe than, but qualitatively similar to, that of Italian children with developmental dyslexia. Both groups showed specific difficulties in reading and writing words and a reduced rapid automatized naming (RAN) speed. This is the first time that a RAN speed deficit has been documented in DMD. Moreover, the boys with DMD and the subgroup of dyslexic children with a previous language delay showed additional deficits in phonological processing. The impairments highlighted in this study could explain the reading difficulties observed in boys with DMD and suggest that there is a need for targeted preschool interventions.

Early Neurodevelopmental Findings Predict School Age Cognitive Abilities in Duchenne Muscular Dystrophy: A Longitudinal Study

Objective

Neurodevelopmental and cognitive difficulties are known to occur frequently in boys with Duchenne muscular dystrophy but so far none of the published studies have reported both early neurodevelopmental assessments and cognitive tests in the same cohort. The aim of the present longitudinal study was to establish the correlation between early neurodevelopmental assessments performed in preschool boys and the cognitive scales performed at school age or later.

Methods

We performed cognitive tests at school age (mean age 5.7 year ±1.7 SD) (69 months+19 SD) in a cohort of Duchenne boys, previously assessed using the Griffiths scales before the age of 4 years (mean age when the Griffiths scales were performed 30 months ±8.9 SD).

Results

The range of total Developmental quotients on the Griffiths ranged between 56 and 116 (mean 89 ± 15.6 SD). The total Intelligence Quotients on the Wechsler scales ranged between 35 and 119 (mean 87 ± 17.2 SD). There was a significant correlation between the findings on the two scales. P = <0.0001. When we subdivided the cohort according to site of mutations, there was a difference between boys with mutations upstream exon 44 and those with mutations in exon 44–45 affecting Dp140 on both Developmental and Intelligence Quotient (p 0.01 and p 0,003 respectively).

Conclusions

Our results confirm that Duchenne boys tend to slightly underperform on both neurodevelopmental and cognitive assessments. Early neurodevelopmental findings correlated with the cognitive results obtained at school age with a clear concordance between subscales exploring similar domains on the two scales.

Neuropsychological profile of duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an inherited myogenic disorder characterized by progressive muscle wasting. DMD is a fatal X-linked recessive disorder with an estimated prevalence of 1 in 3,500 male live births. This disease has long been associated with intellectual impairment. Research has shown that boys with DMD have variable intellectual performance, indicating the presence of specific cognitive deficits. The aim of the study was to use a battery of intelligence, learning, and memory tests to identify a neuropsychological profile in boys with DMD. A total of 22 boys diagnosed with DMD in the age range of 6 to 10 years old were evaluated using the Wechsler Intelligence Scale for Children-Third Edition, Rey's Auditory Verbal Learning Test, and the Memory for Designs Test. The data were interpreted using means, standard deviations, percentages, and percentiles. Normative data were also used for further interpretation. The results showed that boys with DMD had a significantly lower IQ (88.5). Verbal IQ (86.59) was found to be lower than Performance IQ (92.64). There was evidence of impaired performance on the Processing Speed, Freedom From Distractibility, and Verbal Comprehension Indexes. Specific deficits in information processing, complex attention, immediate verbal memory span, verbal working memory, verbal comprehension, vocabulary, visuoconstruction ability, and verbal learning and encoding were observed. However, perceptional organization, general fund of information, abstract reasoning, visual discrimination and acuity, visual learning and memory, and verbal memory were adequate. The neuropsychological findings support the hypothesis that these children have specific cognitive deficits as opposed to a global intellectual deficit.

Motor and cognitive assessment of infants and young boys with Duchenne Muscular Dystrophy: results from the Muscular Dystrophy Association DMD Clinical Research Network

Therapeutic trials in Duchenne Muscular Dystrophy (DMD) exclude young boys because traditional outcome measures rely on cooperation. The Bayley III Scales of Infant and Toddler Development (Bayley III) have been validated in developing children and those with developmental disorders but have not been studied in DMD. Expanded Hammersmith Functional Motor Scale (HFMSE) and North Star Ambulatory Assessment (NSAA) may also be useful in this young DMD population. Clinical evaluators from the MDA-DMD Clinical Research Network were trained in these assessment tools. Infants and boys with DMD (n = 24; 1.9 ± 0.7 years) were assessed. The mean Bayley III motor composite score was low (82.8 ± 8; p ≤ .0001) (normal = 100 ± 15). Mean gross motor and fine motor function scaled scores were low (both p ≤ .0001). The mean cognitive comprehensive (p=.0002), receptive language (p ≤ .0001), and expressive language (p = .0001) were also low compared to normal children. Age was negatively associated with Bayley III gross motor (r = -0.44; p = .02) but not with fine motor, cognitive, or language scores. HFMSE (n=23) showed a mean score of 31 ± 13. NSAA (n = 18 boys; 2.2 ± 0.4 years) showed a mean score of 12 ± 5. Outcome assessments of young boys with DMD are feasible and in this multicenter study were best demonstrated using the Bayley III.

Neuropsychological and neurobehavioral functioning in Duchenne muscular dystrophy: a review

Duchenne muscular dystrophy (DMD) is a genetic condition affecting predominantly boys that is characterized by fatal muscle weakness. While there is no cure, recent therapeutic advances have extended the lifespan of those with DMD considerably. Although the physiological basis of muscle pathology is well-documented, less is known regarding the cognitive, behavioral, and psychosocial functioning of those afflicted. Several lines of evidence point to central nervous system involvement as an organic feature of DMD, challenging our view of the disorder as strictly neuromuscular. This report provides a review of the literature on neuropsychological and neurobehavioral functioning in DMD. Recent research identifying associations with DMD and neuropsychiatric disorders is also discussed. Lastly, the review presents implications of findings related to nonmotor aspects of DMD for improving the quality of life in those affected. While the literature is often contradictory in nature, this review highlights some key findings for consideration by clinicians, educators and parents when developing therapeutic interventions for this population.

Early neurodevelopmental assessment in Duchenne muscular dystrophy

The aim of this study was to assess neurodevelopmental profile in young boys affected by Duchenne muscular dystrophy and to establish the correlation between neurodevelopmental findings, and the type and site of mutations. A structured neurodevelopmental assessment (Griffiths Scale of Mental Development) was performed in 81 DMD boys before the age of four years (range: 7-47 months). The mean total DQ was 87 (SD 15.3). Borderline DQ (between 70 and 84) was found in 32% and DQ below 70 in 12.3% of the patients. Children with mutations upstream or in exon 44 had higher DQ than those with mutations downstream exon 44 which are associated with involvement of dystrophin isoforms expressed at high levels in brain. The difference was significant for total and individual subscale DQ with the exception of the locomotor subscale. Items, such as ability to run fast, or getting up from the floor consistently failed in all children, irrespective of the age or of the site of mutation. Our results help to understand the possible different mechanisms underlying the various aspects of neurodevelopmental delay, suggesting that the involvement of brain dystrophin isoforms may cause a delay in the maturation of coordination and dexterity.

Investigating Sensory Processing Patterns in Boys with Duchenne Muscular Dystrophy Using the Sensory Profile

Objectives:

This exploratory study investigated the sensory processing patterns of boys with Duchenne muscular dystrophy (DMD) using the Sensory Profile. It was hypothesised that this group would be different to a typically developing sample of American children in the normative sample of the Sensory Profile. In doing so, the utility of the Sensory Profile for a sample of boys with DMD was investigated.

Method:

Data were gathered from the caregivers of 37 boys with DMD living in Australia, using the Sensory Profile Caregiver Questionnaire. The means of the DMD boys were compared with the means of American boys without disabilities.

Results:

Boys with DMD were different to the normative sample in the Auditory processing section, two of the five sections in the Modulation domain ( Movement affecting activity level and Sensory input affecting emotional responses) and two of the three sections in the Behaviour and Emotional Responses domain ( Emotional/ social responses and Behavioural outcomes of sensory processing).

Conclusion:

This sample of boys with DMD may have had specific areas of sensory processing difficulties. Further research is needed to identify a more suitable tool for the assessment of children with DMD and to examine further the sensory patterns of boys with DMD.

Perfil comportamental e competência social de crianças e adolescentes com distrofia muscular de Duchenne

A distrofia muscular de Duchenne é uma doença genética caracterizada por enfraquecimento muscular progressivo e degeneração irreversível, acompanhados por danos sensoriais e neuropsicológicos. Os objetivos do estudo consistiram em avaliar o perfil comportamental de crianças/adolescentes com DMD e a influência do prejuízo motor, da idade no início do uso de cadeira de rodas e da idade no diagnóstico. Participaram 34 pacientes e 20 controles. Os pacientes formaram dois grupos conforme o quociente de inteligência (QI). Os pais responderam ao Inventário de Comportamentos da Infância e da Adolescência. Pacientes com DMD obtiveram escores mais baixos em Atividades e Sociabilidade (p < 0,01; ANCOVA). Os pacientes com QI < 80 apresentaram menores índices de Escolaridade. O prejuízo motor e as idades referentes à cadeira e ao diagnóstico correlacionaram-se com sintomas psiquiátricos/somáticos e problemas escolares. Os achados enfatizam a necessidade de programas educacionais acerca da doença como base para o desenvolvimento de estratégias de inclusão social.

Specific profiles of neurocognitive and reading functions in a sample of 42 Italian boys with Duchenne Muscular Dystrophy

A group of 42 Italian boys with Duchenne Muscular Dystrophy was compared with a control group of 10 boys with Spinal Muscular Atrophy and Osteogenesis Imperfecta on tests assessing general intellectual ability, language, neuropsychological functions, and reading skills with the aim of describing a comprehensive profile of the various functions and investigating their interrelationships. The influence of general intellectual level on performance was analyzed. Further, correlations between various neuropsychological measures and language performances were computed for the group with Duchenne Muscular Dystrophy, as well as the correlations between reading scores and other cognitive and linguistic measures. A general lowering in VIQ, PIQ, and FSIQ scores was found to characterize the group with Duchenne Muscular Dystrophy. Expressive language skills were within the normal range, while syntactic and grammatical comprehension were significantly impaired. The presence of below-average reading performances was further confirmed. However, unlike previous studies on irregular orthographies, the present results show that (a) the mild reading difficulties found in the sample essentially concern speed rather than accuracy; (b) they concern word rather than nonword reading; (c) lower reading performances are related to lower scores in general IQ; (d) no correlations emerge with phonological abilities, verbal short-term memory, or working memory, but rather with long-term memory and lexical skills. This may suggest that language-specific effects modulate the cognitive expressions of Duchenne Muscular Dystrophy and raises the possibility that the dysfunctions underlying the reading difficulties observed in affected readers of regular orthographies involve different neurocognitive systems than the cortico-cerebellar circuits usually invoked.

Reduction of abnormal behavioral response to brief restraint by information from other mice in dystrophin-deficient mdx mice

We recently reported that dystrophin-deficient mdx mice exhibited a hypersensitive freezing response to fearful events such as brief restraint. In the present study, we ethologically characterized the restraint-induced freezing response in mdx mice. This response was evident when restrained mdx mice were released into a new cage or their home cage, but it was remarkably reduced in cages in which other individuals (wild-type mice that had never been reared with the tested mice) had been reared (the resident mice were removed prior to testing). Reciprocally, exploratory behaviors of restrained mdx mice were outstandingly enhanced in the cages in which other individuals had been reared, suggesting the possibility that scent deposited by residents induced exploration in mdx mice. These results suggest that restraint-induced freezing response in mdx mice is influenced by the attention state of the mouse.

Association of autistic spectrum disorders with dystrophinopathies

Parents of 85 boys with dystrophinopathies and 51 sibling controls completed the Social Communication Questionnaire, describing child behaviors associated with autism spectrum disorders and a rating of parental stress. Twenty-one boys with dystrophinopathies and no siblings received scores above the cut-point for possible autistic spectrum disorders. Mothers of identified children were given detailed interviews using the Autism Diagnostic Interview-Revised, and 16 boys (about 19% of the sample) met the criteria for autism spectrum disorders. Significant qualitative abnormalities in reciprocal social interactions and communication were evident in all, whereas restricted and repetitive behaviors were generally less pronounced in the group. Moreover, parents of boys with dystrophinopathy and autism spectrum disorders demonstrated significantly higher ratings of stress than parents of boys with dystrophinopathy alone. Increased attention to behavioral concerns associated with dystrophinopathies is necessary to ensure the well-being of the whole family.

The neurobiology of the dystrophin-associated glycoprotein complex

While the function of dystrophin in muscle disease has been thoroughly investigated, dystrophin and associated proteins also have important roles in the central nervous system. Many patients with Duchenne and Becker muscular dystrophies (D/BMD) have cognitive impairment, learning disability, and an increased incidence of some neuropsychiatric disorders. Accordingly, dystrophin and members of the dystrophin-associated glycoprotein complex (DGC) are found in the brain where they participate in macromolecular assemblies that anchor receptors to specialized sites within the membrane. In neurons, dystrophin and the DGC participate in the postsynaptic clustering and stabilization of some inhibitory GABAergic synapses. During development, alpha-dystroglycan functions as an extracellular matrix receptor controlling, amongst other things, neuronal migration in the developing cortex and cerebellum. Several types of congenital muscular dystrophy caused by impaired alpha-dystroglycan glycosylation cause neuronal migration abnormalities and mental retardation. In glial cells, the DGC is involved in the organization of protein complexes that target water-channels to the plasma membrane. Finally, mutations in the gene encoding epsilon-sarcoglycan cause the neurogenic movement disorder, myoclonus-dystonia syndrome implicating epsilon-sarcoglycan in dopaminergic neurotransmission. In this review we describe the recent progress in defining the role of the DGC and associated proteins in the brain.

Cognitive and adaptive deficits in young children with Duchenne muscular dystrophy (DMD)

The goal of the current investigation was to examine adaptive behavior and cognitive skills in young children with Duchenne muscular dystrophy (DMD), a genetic disorder that causes progressive muscular weakness and concomitant cognitive deficits. Previous studies have documented specific language deficits in older children with DMD, but there are limited data on younger children. Twenty children with DMD who were between 3 and 6 years old and 20 unaffected family control children were recruited. Parents completed questionnaires relating to development and adaptive functioning, while children completed neuropsychological testing. Results of paired t tests indicate that children with DMD are rated as delayed relative to familial controls on measures of adaptive functioning, as assessed by the Vineland Adaptive Behavior Scales. Furthermore, children with DMD exhibit impairments on multiple measures of cognition, including measures of receptive language, expressive language, visuo-spatial skills, fine-motor skills, attention, and memory skills. Across all domains examined, the young children with DMD performed more poorly than their familial controls. These deficits appear to be more generalized than those reported in older children with this disorder. Dystrophin, a missing protein product, is hypothesized to be responsible for these cognitive and behavioral impairments.

Duchenne muscular dystrophy: a cerebellar disorder?

Cyrulnik, S.C., and V.J. Hinton. Duchenne muscular dystrophy: A cerebellar disorder? NEUROSCI. BIOBEHAV. REV. Duchenne muscular dystrophy (DMD) is a genetic disorder that is often associated with cognitive deficits. These cognitive deficits have been linked to the absence of dystrophin, a protein product which is normally found in multiple tissues throughout the body. In the current paper, we argue that it is the absence of dystrophin in the cerebellum that is responsible for the cognitive deficits observed. We begin by reviewing data that document structural and functional abnormalities in the brains of individuals with DMD and mdx mice. We briefly review the cognitive deficits associated with DMD, and then present neuroimaging and neuropsychological evidence to indicate that the cerebellum is involved in the same aspects of cognition that are impaired in children with DMD. It is our contention that the development of brain pathways in the cerebellum (e.g., cerebro-cerebellar loops) without dystrophin may result in altered brain function presenting as cognitive deficits in DMD.

Delayed developmental language milestones in children with Duchenne's muscular dystrophy

OBJECTIVES

To document the attainment of developmental milestones in children with Duchenne's muscular dystrophy (DMD) and to determine whether early delays are associated with later performance on measures of cognition.

STUDY DESIGN

Retrospective parental report was utilized to document the acquisition of 10 common developmental milestones in children with DMD (n = 130) and their unaffected siblings (n = 59). Children completed tests of cognitive functioning.

RESULTS

Parents rated children with DMD as delayed on achieving both language and motor milestones more frequently than their unaffected siblings. Furthermore, those children with DMD who were rated as late talkers or late walkers performed more poorly on tests of cognitive function than their on-time peers.

CONCLUSIONS

In addition to the commonly reported delays in motor milestones, the current study documents delays in the acquisition of language milestones as well. These early delays are associated with significant impairments in later cognitive functioning.

Verbal and memory skills in males with Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a progressive pediatric disorder that affects both muscle and brain. Children with DMD have mean IQ scores that are about one standard deviation lower than population means, with lower Verbal IQ than Performance IQ scores. For the present study, verbal skills and verbal memory skills were examined in males with DMD with the Clinical Evaluation of Language Fundamentals, 3rd edition, and the California Verbal Learning Test for Children. Performance of 50 males with DMD (age range 6-14 y, mean 9 y 4 mo [SD 2 y 1 mo]) was compared to normative values. Two subsets of the probands were also compared with two comparison groups: unaffected siblings (n=24; DMD group age range 6-12 y, mean 9 y 1 mo [SD 1 y 8 mo]; sibling age range 6-15 y, mean 9 y 11 mo [SD 2 y 4 mo]) and males with cerebral palsy (CP); (n=23; DMD group age range 6-9 y, mean 7 y 8 mo [SD 1 y 2 mo]; CP age range 6-8 y, mean 6 y 8 mo [SD 0 y 8 mo]). Results demonstrated that although males with DMD performed slightly more poorly than normative values, they performed comparably to the controls on most measures. Consistent deficits were observed only on tests requiring immediate repetition for verbal material (Recalling Sentences, and Concepts and Directions). On other language tasks, including tests of understanding and use of grammar, and understanding of semantic relationships, the males with DMD performed well. Moreover, the males with DMD performed well on multiple indices of verbal recall, and there was no evidence of declarative memory deficits. DMD is a single-gene disorder that is selectively associated with decreased verbal span capacity, but not impaired recall.

Poor facial affect recognition among boys with duchenne muscular dystrophy

Children with Duchenne or Becker muscular dystrophy (MD) have delayed language and poor social skills and some meet criteria for Pervasive Developmental Disorder, yet they are identified by molecular, rather than behavioral, characteristics. To determine whether comprehension of facial affect is compromised in boys with MD, children were given a matching-to-sample test with four types of visual recognition (Object, Face, Affect, and Situation matching) developed by Lucci and Fein. Within-group analyses on 50 boys with MD found decreased Affect matching relative to the other matching conditions. Between-group comparisons on 20 sibling pairs found the boys with Duchenne performed more poorly only on the Affect-matching condition. Thus, mildly impaired facial affect recognition may be part of the phenotype associated with Duchenne or Becker MD.

Social behavior problems in boys with Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a chronic, progressive pediatric disease that affects both muscle and brain. The objectives of the study were to examine parent reported behavior in children with DMD, investigate the influence of chronic illness, intellectual ability and etiology on behavior, and determine whether a specific behavioral profile is associated with DMD. Parental ratings of boys with DMD (n = 181) on the Child Behavior Checklist behavior scales were examined and compared to reported findings of children with other chronic illnesses, unaffected siblings of boys with DMD (n = 86), and children with cerebral palsy (CP) (n = 42). Increased ratings of general behavior problems were reported, and neither physical progression nor intellectual level contributed to behavioral ratings. Among the children with DMD, the Social Problem behavior scale had the greatest number of "clinically significant" ratings (34%). Between-group comparisons showed significantly more boys with DMD were rated as having social behavior problems than either the sibling or CP comparison groups. In addition to the increase in reported behavioral problems likely related to the effects of chronic illness, boys with DMD may be at heightened risk for specific social behavior problems. The specificity of the findings of the behavior profile in DMD may be partially due to the lack of dystrophin isoforms in the central nervous system, and not solely a reactive response to the illness.