Types of Bipolar Disorder and Related

Bipolar I Disorder—defined by manic or mixed episodes that last at least seven days, or by manic symptoms that are so severe that the person needs immediate hospital care. Usually, depressive episodes occur as well, typically lasting at least 2 weeks.

Bipolar II Disorder—defined by a pattern of depressive episodes and hypomanic episodes, but no full-blown manic or mixed episodes.

Bipolar Disorder Not Otherwise Specified (BP-NOS)—diagnosed when symptoms of the illness exist but do not meet diagnostic criteria for either bipolar I or II. However, the symptoms are clearly out of the person's normal range of behavior.

Cyclothymic Disorder, or Cyclothymia—a mild form of bipolar disorder. People with cyclothymia have episodes of hypomania as well as mild depression for at least 2 years. However, the symptoms do not meet the diagnostic requirements for any other type of bipolar disorder.