Psychometric evaluation in myotonic muscular dystrophy.

Systematic psychometric evaluations were performed in 16 patients with myotonic muscular dystrophy (MMD). All patients received the Wechsler Adult Intelligence Scale-Revised and Wechsler Memory Scale-1. In addition, 13 patients received the Reitan-Halstead Neuropsychological Test Battery (R-H), including the Aphasia Screening Test. Despite the high reported incidence of mental retardation in MMD, none of our pilot population showed mental retardation. However, 5 of the 13 patients showed evidence of possible organic mental dysfunction on the R-H. Problems in previous studies which could explain these discrepancies include the following: (1) small sample size, (2) studies limited to young children, and (3) a complete lack of systematic psychometric data in the previous reports. Systematic cooperative studies are suggested to elucidate the degree and type of cognitive involvement in MMD.