How does Bipolar II disorder differ from Bipolar I disorder?

Bipolar II disorder is characterized by the presence of at least one major depressive episode and at least one hypomanic episode, which is a less severe form of mania compared to what is seen in Bipolar I disorder. In Bipolar I disorder, an individual experiences one or more manic episodes that can be severe and impair functioning significantly. The key distinction is that Bipolar II disorder does not include full manic episodes; instead, it features hypomanic phases, which can still cause changes in mood and function but are not as extreme as full manic episodes.

The correct choice emphasizes that individuals with Bipolar II experience only mild manic phases, termed hypomania, rather than the more extreme manic phases associated with Bipolar I disorder. This delineation is critical for diagnosis and treatment, as the nature and severity of the episodes significantly influence the clinical management of these disorders.