Bipolar disorders

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Bipolar disorders are characterized by episodes of mania and depression, which may alternate, although many patients have a predominance of one or the other. Exact cause is unknown, but heredity, changes in the level of brain neurotransmitters, and psychosocial factors may be involved. Diagnosis is based on history. Treatment consists of mood-stabilizing drugs, sometimes with psychotherapy.
Bipolar disorders usually begin in the teens, 20s, or 30s (see also Bipolar Disorder in Children and Adolescents). Lifetime prevalence is about 4%. Rates of bipolar I disorder are about equal for men and women.
Bipolar disorders are classified as

Bipolar I disorder: Defined by the presence of at least one full-fledged (ie, disrupting normal social and occupational function) manic episode and usually depressive episodes
Bipolar II disorder: Defined by the presence of major depressive episodes with at least one hypomanic episode but no full-fledged manic episodes
Unspecified bipolar disorder: Disorders with clear bipolar features that do not meet the specific criteria for other bipolar disorders

In cyclothymic disorder, patients have prolonged (