Bipolar disorder type I (BPI) is characterized by at least one episode of mania, which leads to hospitalization or significant impairment in functioning. Individuals with bipolar I experience at least one manic episode in their lives. Although not required for the formal diagnosis, the vast majority will also experience major depressive episodes. The manic episodes are the defining characteristic of bipolar disorder type I.
In comparison, bipolar disorder type II (BPII) is characterized by severe depression combined with punctuated hypomanic episodes, in other words, the “up” moods never reach full-blown mania, and instead, depression is the major feature. Hypomania is a less severe form of mania that does not result in psychosis or cause impairments in social or occupational functioning.
Cyclothymic disorder is diagnosed in individuals who have both hypomanic and depressive symptoms for at least two years without meeting the full criteria for hypomania, mania, or major depression.
