OverviewDepression is defined as a mood disorder, and there are several subtypes. Bipolar disorder, also known as manic-depressive illness, is considered in a separate category.
Update Date 2/2/2016
Updated by: Fred K. Berger, MD, addiction and forensic psychiatrist, Scripps Memorial Hospital, La Jolla, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.