The age factor in depressive illness: some genetic considerations.

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 smaller genetic and greater environmental component. A correlation has been found between positive family history 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 treatment, that a family history be gathered on patients with depressive illness.