How does Bipolar I disorder differ from Bipolar II disorder?

Bipolar I disorder is characterized by the presence of at least one manic episode. A manic episode involves an elevated or irritable mood, increased energy or activity, and other symptoms that last for at least one week or require hospitalization. This manic phase can significantly impair social and occupational functioning, and may even involve psychotic features.

In contrast, Bipolar II disorder is defined by the presence of at least one major depressive episode and at least one hypomanic episode, which is a milder form of mania that doesn't meet the full criteria for a manic episode. Importantly, individuals with Bipolar II disorder do not experience full manic episodes.

The correct answer highlights the defining feature of Bipolar I disorder, which is the occurrence of manic episodes, making it a key distinction in diagnosing these two forms of bipolar disorder. Understanding this difference is crucial for appropriate treatment decisions and managing symptoms effectively.