Chronic depression: update on classification and treatment.

A significant proportion of patients with depressive disorders suffer from chronic conditions. The DSM-IV recognizes several forms of chronic depression. Chronic depressions differ from nonchronic major depressive disorder (MDD) on many clinical, psychosocial, and familial variables. However, less support exists for current distinctions between the various forms of chronic depression. Antidepressant medications and at least some forms of psychotherapy are efficacious in treating chronic depression, and the combination of pharmacotherapy and psychotherapy appears to be superior to either monotherapy alone. Still, chronic depression is often inadequately treated, and many patients fail to respond or continue to experience residual symptoms after treatment. An important direction for future research is to elucidate the multiple pathways to chronic depression and to tailor treatments to specific etiopathogenetic subgroups.