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 2/21/2016
Updated by: Timothy Rogge, MD, Medical Director, Family Medical Psychiatry Center, Kirkland, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.