Downward shift in IQ in persons with Duchenne muscular dystrophy compared to those with spinal muscular atrophy.

Patients with Duchenne progressive muscular dystrophy (DMD) and those with spinal progressive muscular atrophy (SPMA) were compared on the basis of memory and IQ. The DMD group was inferior to the SPMA group in memory tests and Full Scale IQ. The DMD group showed poorer scores, despite the fact that functional disabilities and social environments were similar for the two groups. Results thus support the current view that lower IQ is one of the primary manifestations of DMD.