How does a diagnosis of bipolar I disorder differ from bipolar II disorder?

The distinction between bipolar I disorder and bipolar II disorder primarily revolves around the nature of the mood episodes experienced by the individual. Bipolar I disorder is characterized by the presence of at least one manic episode, which is a significantly elevated or irritable mood lasting at least one week, along with other symptoms that cause marked impairment in social or occupational functioning or may require hospitalization to prevent harm.

In contrast, bipolar II disorder involves at least one major depressive episode and at least one hypomanic episode. Hypomania is less severe than mania and does not cause the same level of impairment. While individuals with bipolar II disorder experience elevated moods, the absence of full-blown manic episodes is what differentiates it from bipolar I disorder.

The correct choice emphasizes the requirement of manic episodes in bipolar I disorder, which is a hallmark that defines the condition. Understanding this distinction is crucial for appropriate diagnosis and treatment, as the management strategies for these disorders can differ significantly based on the presence and severity of manic symptoms.