There are two main types of bipolar disorder.
The person has manic or mixed episodes as well as depression.
The person only has one or more depressive episodes with at least one hypomanic episode. For some, hypomanic episodes are not severe enough to cause severe impairment in functioning.
When four or more episodes of illness occur within a year, the person is said to have bipolar disorder with rapid cycling.
This is characterised by chronic fluctuating moods involving periods of hypomania and depression.
Revision date: July 3, 2011
Last revised: by Janet A. Staessen, MD, PhD