title: Issues in the definition of mental retardation and the representativeness of studies.
abstract: The lack of a clear definition of mental retardation in many studies and the lack of a description of the methods used in selecting subjects make it difficult to determine to whom the results apply. A review of prevalence studies of MR in childhood shows that over the past 30 years there has been a trend of decreasing rates. Reasons are suggested to explain these falling prevalence rates. Adult prevalence rates were lower than childhood rates and reasons are suggested for this drop. Factors needing consideration in future studies are suggested.
authors.affiliation: Albert Einstein College of Medicine, Bronx, New York 10461.
authors.forename: S A
authors.initials: SA
authors.lastname: Richardson
mesh_terms: D002648:Child; D003430:Cross-Sectional Studies; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis* / Q000453:epidemiology; D007360:Intelligence; D014481:United States