Epidemiology of affective disorders.

Data from recent epidemiological studies involving psychosocial risk factors for affective disorders are reviewed. The results of these studies are divided into the categories of depressive symptoms, bipolar depressive disorder, and nonbipolar depressive disorder. When the data are examined using these categories, remarkable consistency in psychosocial risk factors for depressive symptoms and nonbipolar depressive disorder is observed, suggesting possible continuity between these conditions. Psychosocial risk factors for bipolar disorder differ substantially from those identified for depressive symptoms and nonbipolar depressive disorder and, therefore, provide further support for the bipolar-nonbipolar distinction.