Juvenile and late onset forms of depressive disorder: genetic and biological characterization of bipolar and unipolar illness-a review.

The age of onset of depressive illness may have an association with the genetic character and clinical course of the disorder. There are several genetic models of depressive disorder that are based on differences in age of onset. According to a multifactorial model, for example, a late onset would indicate a small genetic and greater environmental component. A correlation has been found between positive family histroy of affective illness and early age of the first episode. The presence or absence of a family history of affective illness has also been found to be distinguished by pharmacology, physiology, symptomatology, and severity. It is therefore recommended, for purposes of diagnosis and treatment, that a family history be gathered for patients with depressive illness.