a1 Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287
This critical review examines mental retardation (MR) from a neuropsychological perspective. Competing definitions of MR are discussed and the prevalence is estimated. Descriptions are given of idiopathic MR and the five major identifiable prenatal causes of MR: fetal alcohol syndrome, Down's syndrome, fragile X syndrome, Prader-Willi syndrome, and Angelman syndrome. Similarities and differences among syndromes are examined. Cognitive deficits common to all disorders were in attention, short-term memory, and sequential information processing, whereas language and visuospatial abilities were varied. Neuroanatomical abnormalities common to all disorders were in the hippocampus and cerebellum; individual disorders typically showed a unique pattern of other neurological abnormalities. Both knowledge of individual MR-related disorders and comparative research between disorders are important for researchers and clinicians. Further research is called for in both areas. (JINS, 1996, 2, 159–176.)
(Received July 31 1995)
(Accepted December 09 1995)
Reprint requests to: Margaret B. Pulsifer, Department of Psychiatry and Behavioral Sciences, Division of Medical Psychology, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Meyer 218, Baltimore, MD 21287–7218.