Bipolar disorder: A mood disorder sometimes called manic-depressive illness or manic-depression that characteristically involves cycles of depression and elation or mania. Sometimes the mood switches from high to low and back again are dramatic and rapid, but more often they are gradual and slow, and intervals of normal mood may occur between the high (manic) and low (depressive) phases of the condition. The symptoms of both the depressive and manic cycles may be severe and often lead to impaired functioning.
Both phases of the disease are deleterious. Mania affects thinking, judgment, and social behavior in ways that may cause serious problems and embarrassment. For example, unwise business or financial decisions may be made when an individual is in a manic phase. Depression can also affect thinking, judgment, and social behavior in ways that may cause grave problems. For example, it elevates the risk of suicide. About 5.7 million American adults, or about 2.6 percent of the population aged 18 and older, have bipolar disorder.
Although bipolar disorder often worsens over time if untreated, most people with bipolar disorder can achieve stabilization of their mood swings and reduction of symptoms with proper treatment. Treatment usually consists of medications known as "mood stabilizers."
See also: Manic-depression.