Evidence-Based Long-Term Treatment of Bipolar II Disorder

Bipolar II disorder is a distinct, lifelong mental illness that affects at least 1.5 million people in theUnited States, is associated with a high incidence of comorbidity, and ends with completed suicide in10% to 15% of diagnosed individuals. Bipolar II disorder is characterized by at least 1 major depressiveepisode with 1 or more hypomanic episodes, as opposed to manic or mixed episodes. While it isexpected that there may be similarities in approaches to managing patients with bipolar I and bipolarII disorders, data suggest differential patient responses to pharmacologic treatments, supporting theneed for research specifically in patients with bipolar II disorder. Despite the prevalence and severityof the disorder, a well-developed scientific database informing long-term treatment choices forbipolar II disorder as an illness differing from bipolar I disorder and major depressive disorder isvirtually absent. A review of the limited and sometimes contradictory information stresses that moreresearch is needed into prophylactic and maintenance treatment of bipolar II disorder.