Bipolar II disorder

Bipolar II disorder (BP-II) is a mood disorder on the bipolar spectrum, characterized by at least one episode of hypomania and at least one episode of major depression.^[1][2][3][4] Diagnosis for BP-II requires that the individual must never have experienced a full manic episode.^[5] Otherwise, one manic episode meets the criteria for bipolar I disorder (BP-I).^[2]

Hypomania is a sustained state of elevated or irritable mood that is less severe than mania yet may still significantly affect the quality of life and result in permanent consequences including reckless spending, damaged relationships and poor judgment.^[6]: 1651 Unlike mania, hypomania cannot include psychosis.^[1][7] The hypomanic episodes associated with BP-II must last for at least four days.^[2][8]

Commonly, depressive episodes are more frequent and more intense than hypomanic episodes.^[2] Additionally, when compared to BP-I, type II presents more frequent depressive episodes and shorter intervals of well-being.^[1][2] The course of BP-II is more chronic and consists of more frequent cycling than the course of BP-I.^[1][9] Finally, BP-II is associated with a greater risk of suicidal thoughts and behaviors than BP-I or unipolar depression.^[1][9] BP-II is no less severe than BP-I, and types I and II present equally severe burdens.^[1][10]

BP-II is notoriously difficult to diagnose. Patients usually seek help when they are in a depressed state, or when their hypomanic symptoms manifest themselves in unwanted effects, such as high levels of anxiety, or the seeming inability to focus on tasks. Because many of the symptoms of hypomania are often mistaken for high-functioning behavior or simply attributed to personality, patients are typically not aware of their hypomanic symptoms. In addition, many people with BP-II have periods of normal affect. As a result, when patients seek help, they are very often unable to provide their doctor with all the information needed for an accurate assessment; these individuals are often misdiagnosed with unipolar depression.^[1][2][9] BP-II is more common than BP-I, while BP-II and major depressive disorder have about the same rate of diagnosis.^[11] Of all individuals initially diagnosed with major depressive disorder, between 40% and 50% will later be diagnosed with either BP-I or BP-II.^[1] Substance use disorders (which have high co-morbidity with BP-II) and periods of mixed depression may also make it more difficult to accurately identify BP-II.^[2] Despite the difficulties, it is important that BP-II individuals be correctly assessed so that they can receive the proper treatment.^[2] Antidepressant use, in the absence of mood stabilizers, is correlated with worsening BP-II symptoms.^[1]