Psychiatry· Topic 15.1 Mood disorders· 15.1.8

Bipolar II disorder

Bipolar II disorder requires at least one hypomanic episode (elevated or irritable mood for 4 or more consecutive days without marked impairment, psychosis, or hospitalization) plus at least one major depressive episode, and no lifetime history of a full manic episode; first-line treatment is lithium with careful avoidance of unopposed antidepressants.

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What this article covers

  • Overview

    Definition: bipolar II disorder is a bipolar and related disorder defined by at least one hypomanic episode plus at least one major depressive episode (MDE), with no lifetime history of a full manic episode.

  • Epidemiology

    Prevalence: bipolar disorder affects about 1% to 3% of the population.

  • Risk factors

    Family history of mood disorder: a first-degree relative with bipolar disorder or another mood disorder is the strongest identified risk factor.

  • Pathophysiology

    Primary mood disorder by exclusion: episodes are not attributable to another medical condition or the physiologic effects of a substance; ruling out these secondary causes is part of establishing the diagnosis.

  • Clinical features

    Hypomanic episode (required, at least one): a distinct period of abnormally and persistently elevated, expansive, or irritable mood and energy lasting 4 or more consecutive days, with 3 or more of…

  • Differential diagnosis

    Bipolar I disorder: a manic episode requiring hospitalization or accompanied by psychotic symptoms establishes bipolar I rather than bipolar II.

  • Diagnosis

    The diagnosis is clinical: it requires DSM-5 criteria for at least one hypomanic episode plus at least one major depressive episode, symptoms not attributable to a substance or another medical condition, and no lifetime manic episode.

  • Management

    First, assess suicide risk and safety in every patient presenting in a depressive episode, given the high lifetime suicide risk in bipolar disorder; escalate to psychiatric evaluation and consider…

  • Complications

    Suicide: up to 10% to 15% of patients with bipolar and related disorders complete suicide.

  • Prognosis

    Interepisode recovery: mood and functioning usually normalize between episodes, distinguishing bipolar II from chronic conditions like cyclothymic disorder or persistent depressive disorder.

  • Prevention

    Universal depression screening: the U.S. Preventive Services Task Force recommends screening all patients for depression at primary care visits, using a brief instrument such as the two-question PHQ screen.

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