The natural history and heterogeneity of depressive disorders: implications for rational antidepressant therapy.

Depression is a chronic, recurrent illness that affects approximately 8% of the U.S. population. There are several types of depressive disorders including major depression, unipolar depression, bipolar depression, double depression, and dysthymia. For those afflicted, each type of depressive disorder can cause a loss of productivity, job status, and income and can result in poor health and suicide. Depression also has a high rate of comorbidity with other disorders, especially anxiety disorders and alcoholism; yet, depression is still undertreated and underrecognized by most physicians. This is particularly unfortunate because there are many antidepressant medications currently available that are effective in treating this insidious illness. To continue to combat this dangerous illness, more clinical trials are needed to help us maximize the benefits and minimize the risks associated with current antidepressant medications.