Preventive aspects of mental retardation.

Estimates of the incidence of mental retardation vary from 1 to 3 per cent of the population. Prevention of this disability requires different methods, depending on the cause. Retarded persons are of four broad categories: Those who are the low end of the normal distribution curve of intelligence in the general population, without any specific illness or defect; those in whom retardation is culturally and socially determined; those who are functionally retarded due to emotional disorder; and those with damage of the brain structure. More flexibility is required within our relatively complex society so that dull people can adapt themselves, achieve acceptance, and find a vocation within their range of ability. There is need for improved services for the early diagnosis and treatment of emotional disturbances in children, and for counselling with parents of slow learning children to make the family climate as favorable as possible. Certain diseases which cause organic defects in the brain are now sufficiently well understood to make possible the prevention of mental retardation in persons with these diseases-cretinism and congenital syphilis among them. More recently, an increasing emphasis on the preventive approach to mental retardation has been made possible through our understanding of the effects of German measles in early pregnancy, knowledge of such metabolic errors as phenylketonuria and galactosemia, of kernicterus caused by Rh incompatibility between mother and child, as well as by our increased knowledge of human genetics.