Bipolar I Disorder is an illness in which people have experienced one or more episodes of mania. Most people diagnosed with bipolar I will have episodes of both mania and depression, though an episode of depression is not necessary for a diagnosis. To be diagnosed with bipolar I, a person’s manic episodes must last at least seven days or be so severe that hospitalization is required.
Bipolar II Disorder is a subset of bipolar disorder in which people experience depressive episodes shifting back and forth with hypomanic episodes, but never a “full” manic episode.
Cyclothymic Disorder or Cyclothymia is a chronically unstable mood state in which people experience hypomania and mild depression for at least two years. People with cyclothymia may have brief periods of normal mood, but these periods last less than eight weeks.
Bipolar Disorder, “other specified” and “unspecified” is when a person does not meet the criteria for bipolar I, II or cyclothymia but has still experienced periods of clinically significant abnormal mood elevation.