Definition of severe mental retardation in school-age children: Findings of an epidemiological study

Summary Data from a survey of school-age children in Mannheim are used to test the hypothesis that two forms of mental retardation — the pathological and the subcultural — can be differentiated on the basis of intelligence tests. The findings indicate that this dichotomy is an over-simplification, since frequency of neurological and other organic impairments is inversely related to intelligence level over a fairly wide range. The best cut-off point for screening purposes, in discriminating between severe or moderately severe retardation (usually pathological), on the one hand, and mild retardation (usually subcultural), on the other, corresponds roughly to IQ 50. Use of higher thresholds tends to increase misclassification and to yield less reliable prevalence rates. Classification of children in the IQ-range 50–70 as mentally handicapped (severely or moderately mentally retarded) appears to be subject to social-class bias, and hence could be selectively disadvantageous for children from lower social-status families. can walk, at best, only with some help.