Verbal and memory skills in males with Duchenne muscular dystrophy

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Abstract
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.