Overview of major depression: Facts, symptoms, and diagnosis

Major Depressive Disorder, MDD, is a serious condition with a lifetime prevalence of 16.6% in the United States. The main symptoms of depression include: depressed mood, a reduced ability to experience pleasure, irritability, decreased concentration, low self-esteem, low energy, and recurrent thoughts of death and suicide, as well as appetite and sleep disturbances. A diagnosis of depression is made when a certain number of these symptoms are reported for longer than two weeks and the symptoms interfere with normal social and occupational functioning.

Refer to the following table for the official diagnostic criteria for MDD as defined in the DSM-IV.

Depression is also known to complicate the outcomes of many other diseases and it contributes substantially to the rates of disease and disability worldwide. Most people who experience one episode of depression will subsequently suffer recurrent episodes. If these recurrent episodes occur along with manic or hypomanic episodes, the proper diagnosis is Bipolar I Disorder, or Bipolar II Disorder, respectively.

Whether the diagnosis is MDD or Bipolar Disorder, depressive symptoms can dominate the lives of the affected individual and his or her family. 10% to 30% of patients experiencing depression show incomplete recovery and suffer from persistent but more mild depressive symptoms. There is also a more chronic yet less severe form of depression called Dysthymia.

Review Date:4/19/2025
Reviewed By:Fred K. Berger, MD, DLFAPA, board-certified in psychiatry, Scripps Memorial Hospital, La Jolla, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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