ABSTRACT
All efforts towards the primary prevention of mental retardation aim at a reduction of the incidence. Ever since it became possible in the study of mental disorders to differentiate between mental illness and mental retardation, the mental retardation research has aimed at new knowledge of causation in a consistent and systematic way. Especially during the last quarter of the century, progress in this field has been remarkable. Mental retardation has been called the Cinderella of mental health, and in many new psychiatric textbooks a chapter on mental retardation is searched for in vain. Yet in terms of research, and also of the prevention of new cases, successes have been outstanding. These successes have not been easy to achieve or to maintain. Throughout the many years of research it has been a constant pattern that as soon as one disease or group of diseases causing brain damage or dysfunction was controlled – as, for instance, certain sequelae of tuberculosis, syphilis, and rubella, and of diseases connected with incompatibility of blood groups – very quickly new aetiological factors came into play; for example, traffic accidents resulting in cranial trauma to the foetus, infant, or child, and followed by severe intellectual impairment for the rest of the person's life. Diminution in the incidence of a diagnostic group may not always be the result of scientists' and planners' preventive work, since in certain groups there is a considerable spontaneous fluctuation of prevalence at birth, as seen for instance for Down's Syndrome (Fryers 1984).
