Bipolar disorder, formerly called manic depression, is a mental health illness characterized by one or more episodes of mania (emotional highs) or mixed episodes (in which manic episodes coincide with episodes of major depression on a daily basis for at least a week). The onset of bipolar disorder usually happens in late adolescence or early adulthood, but it can occur at any age, including during childhood.

Most people with bipolar disorder experience distinct, alternating periods of extreme energy and impulsivity (mania) and sadness, hopelessness and loss of interest in activities (depression). This is true of children with bipolar disorder as well, although symptoms may differ somewhat in children.

For example, during manic episodes children and teenagers are more likely than adults to become irritable and to engage in destructive behavior rather than to be euphoric. In addition, children are more likely than adults under age 60 to experience these moods at the same time, a condition known as a mixed state. Children and adolescents also cycle rapidly between mania and depression, sometimes within the same day. Among adults with bipolar disorder, these changes typically occur over a period of weeks or months.

The cause of bipolar disorder is not well understood. However, it appears that brain chemistry plays a major role in its development. Bipolar disorder appears to have a genetic component, and children are at greater risk for bipolar disorder if their parents or siblings have the disorder.

Parents who observe behaviors associated with bipolar disorder in their children for at least two weeks are urged to seek medical advice. Diagnosing bipolar disorder in children can be difficult and controversial. There are no separate diagnostic criteria for children with bipolar disorder, although the mood cycles most children experience occur more rapidly than the criteria allow. However, many people diagnosed as adults report that their symptoms began in childhood. Bipolar disorder may also be initially diagnosed as depression, before a manic episode is identified.

Treatment of bipolar disorder often involves a combination of medications and psychotherapy. For some children or adolescents, inpatient psychiatric care may be required for a time to prevent them from harming themselves or others. There is no cure for bipolar disorder, although treatments usually control the symptoms and enable sufferers to function normally. Bipolar disorder that begins in childhood or adolescence is frequently more severe than cases that begin in adulthood.