A study of institutionalized mentally retarded patients in Manitoba: over-representation by Canadian Indian children

During analysis of data on 406 severely and profoundly mentally retarded children and their families in Manitoba a marked excess of Canadian Indian children was observed. There was no evidence to suggest that the over-representation by native children was due to an increased propensity of Indian families to institutionalize their children nor were these patients more profoundly retarded or more physically handicapped than the non-Indian children studied. Further analysis showed that Indian children were primarily over-represented in the groups with acquired retardation, autosomal recessive genetic disorders, idiopathic retardation with seizures and idiopathic retardation with malformations or dysmorphic signs. Review of other demographic findings indicated that other factors potentially predisposing to retardation, including low socioeconomic status, illegitimacy, high birth order, poor maternal reproductive history and increased consanguinity, were more common in the histories of native children. Severe and profound mental retardation has been said to occur equally in all strata of society. This evidently was not so in this Canadian population and the Indian child may be at special risk. Health care workers should be aware of possible predisposing factors for retardation in this group if reduction of the incidence of this major problem is to be achieved.