Mental retardation in Swedish urban children: some epidemiological considerations.

The total population of children born in 1971 and living in Gothenburg, Sweden, by the end of 1977 was screened in order to estimate prevalence figures for various neurodevelopmental disorders. Ninety-four percent of all children assessed attended public preschools. Questionnaires aimed at detecting perceptual, conceptual, motor, and attentional deficits were completed by preschool teachers for 72% of children in these schools. Samples of children with and without problems on the questionnaire were given neuropsychiatric examinations. National registers were searched to identify mentally retarded children not in public preschools. The total population frequency figure for unequivocal mental retardation was almost 1% with an additional 1% of the total population deemed to be of borderline intelligence.