Bipolar disorder is common. Approximately two percent of the population suffers from the disorder. Men and women are equally affected. Men tend to have more manic episodes while women experience more depressive episodes.
The onset is usually in the twenties but children and adolescents can also be affected. If the onset is after the age of fifty, it is usually due to another medical condition such as multiple sclerosis or the effect of drugs, alcohol or steroids.
Revision date: July 3, 2011
Last revised: by Janet A. Staessen, MD, PhD