Do the mentally retarded suffer from affective illness?

Twenty-five published reports were reviewed regarding the occurrence of affective illness, ie, depression and mania, in mentally retarded individuals, using the DSM-III criteria to assess the validity of both diagnoses. Individuals with mental retardation (MR) were found to manifest the full range of affective disorders. Developmentally impaired social functioning and intelligence influence the clinical presentation, but not the development, of affective symptomatology. Affective disorder diagnoses can be made for patients with all levels of MR severity. In individuals with MR of mild and moderate severity, the diagnosis can be made using standard DSM-III criteria. For those with severe and profound MR, a clinically useful diagnosis can be based on changes in behavior and vegetative functioning, as well as family history of affective illness. The psychiatrically symptomatic person with MR should always be evaluated for affective symptomatology and be considered as a candidate for the full range of treatments, including psychotherapy and pharmacotherapy with antidepressants as well as lithium carbonate.