Which statement describes the primary difference between bipolar I and bipolar II disorder?

The primary difference between bipolar I and bipolar II disorder lies in the nature and severity of manic episodes. In bipolar I disorder, individuals experience at least one manic episode, which is characterized by a significantly elevated or irritable mood that is severe enough to cause marked impairment in social or occupational functioning or to necessitate hospitalization to prevent harm to self or others. This mania can be intense and lasts for a week or longer, and may also be accompanied by psychotic features.

In contrast, individuals with bipolar II disorder have never experienced a full manic episode. Instead, they experience hypomania, which is a milder form of mania. Hypomania is characterized by elevated mood, increased energy, and productivity, but the symptoms do not cause the same level of impairment as full-blown mania does. Therefore, the severity of mania is indeed less in bipolar II than in bipolar I.

The other statements incorrectly characterize the nature of the disorders. For instance, the severity of depressive symptoms in bipolar I and II can vary, but bipolar II is often marked by more severe depression compared to hypomanic episodes. Also, stating that both have the same severity in manic episodes would not be accurate since bipolar I includes severe manic episodes while bipolar II does not include manic