Cognitive functions in Duchenne muscular dystrophy: a reappraisal and comparison with spinal muscular atrophy

In order to clarify cognitive functions in Duchenne muscular dystrophy (DMD), we performed a new controlled neuropsychological study. IQ (WISC-R), verbal skills (fluency, confrontation naming and syntax comprehension) and memory abilities (BEM) were studied in two matched groups; 24 DMD children and 17 spinal muscular atrophy (SMA) children aged 12-16 yr. A significant difference appeared between the DMD and SMA patients: only in the DMD group were there significant disabilities in certain specific functions and normal scores in others. Despite similar education, the DMD children more often had significantly greater learning disabilities. There were more DMD left-handers. Verbal IQ was significantly low whereas performance IQ was at a normal level. DMD children also performed poorly in reading tasks and in some memory functions such as story recall and verbal recognition. Specific cognitive disabilities in certain DMD children, not seen in SMA children, suggest a relationship with a DMD genetic disorder.