Understanding the burden of depression.

Major depressive disorder is a highly prevalent, chronic, and disabling disease affecting millions of individuals worldwide. The burden of major depressive disorder includes impaired role functioning, decreased quality of life, the development of medical conditions, and increased morbidity and mortality. The long-term, recurrent nature of depression and its frequent resistance to available therapies lead to increased utilization of health services, which represents a large financial burden in health care costs. Major depressive disorder is often undertreated; however, even when treatment is adequate, remission rates are low and partial response is common.