The epidemiology of severe mental handicap

Prevalence studies of severe mental handicap in an industrial area in the North West area of the United Kingdom have shown a marked increase between 1961 and 1977, with the hint of a reduction in the most recent years. Further analysis of causes of severe mental handicap shows that the prevalence of Down Syndrome is decreasing, certain causes remain constant in prevalence, and perinatal metabolic causes are shown to be increasing through a period of 15 yr ending in 1975. While improved survival of children influences the total prevalence, high mortality in some conditions makes the analysis of prevalence at birth more significant in considering changes in the pattern of aetiology. These studies are fundamental to the formulation of policies of prevention of severe mental handicap, whether these be social or dependent solely on health care services.