Intelligence and Duchenne muscular dystrophy: Full-scale, verbal, and performance intelligence quotients

Duchenne muscular dystrophy (DMD) is a disease which has as its hallmarks progressive muscle weakness and degeneration of skeletal muscle. Also observed among those with DMD is a higher rate of mental retardation than in the normally developing population. While estimates for the prevalence of mental retardation in the normally developing population are approximately 9%, estimates of mental retardation based on the administration of the Wechsler Intelligence Scales (WIS) or the Stanford-Binet to children with DMD have ranged from 20% to as high as 50% in some studies. There have been intermittent review articles focusing on this issue, with authors noting aspects of the prevalence discrepancy, but no large-scale collation of the considerable published DMD intelligence data has yet been undertaken. The purpose of this paper is to provide an up-to-date review of this literature, and to report, as well as to summarize, the preliminary results of a metaanalysis of the available data, focusing on on global intelligence measures and DMD