A renewed interest in the existence and phenomenology of childhood depressive illness has followed upon the major increase in our knowledge of adult affective disorders. This paper briefly reviews these developments, using a five-stage model of clinical picture, family and follow-up studies, and treatment and laboratory studies. Differences in age of onset, duration, frequency, and type of episode have permitted a division into unipolar and bipolar manic-depressive illness of what had been formerly considered one diagnosis. The different family histories, response to psychopharmacological agents, and certain laboratory findings have supported this distinction. Furthermore, application of this model to unipolar depression and bipolar manic-depressive illness have suggested the possibility of further subgroups. The ultimate goal of such research is to define better for purposes of improved treatment and prognostication the different psychopathological entities.
Our knowledge of childhood depression is meager. Because of imprecise terminology, consistent definitions of a syndrome of childhood depression are lacking. The impact on clinical phenomenology development changes in the growing child complicates this further. Although there have been numerous clinical descriptions of depressed children and a few more sophisticated studies attempting to mirror research in adult depression, without a careful delineation of what childhood depression is, family, laboratory, and treatment studies are meaningless. This should be a major thrust for future research in childhood depression.