The influence of habitat on the prevalence of mental handicap.

The influence of habitat on the frequency and characteristics of mental handicap in Galicia (NW Spain) has been studied by means of a survey of registered mentally handicapped people. Higher prevalence is observed in rural, inland, mountainous, isolated and socioeconomically and culturally depressed areas with low population density, high migration rates and a high degree of endogamy. In these areas the prevalence of severe deficiency among the mentally handicapped is also higher due to CNS infections, cranial traumatisms and goitre and to the infrequent use of birth control methods. The expectation of rehabilitation in these areas is nil, though in some cases occupational adaptation is possible.