What type of episodes must be present to diagnose bipolar II disorder?

To diagnose bipolar II disorder, the presence of hypomanic episodes and major depressive episodes is essential. Bipolar II disorder is characterized by the occurrence of at least one hypomanic episode, which is a less severe form of mania, accompanied by one or more major depressive episodes.

Hypomanic episodes feature elevated mood, increased energy, and other symptoms that are less severe than those found in full manic episodes but still represent a distinct change from the individual's baseline behavior. The depressive episodes are critical as they contribute to the diagnosis and can significantly affect the individual's functioning and quality of life.

In contrast, the absence of full manic episodes is a key distinguishing feature of bipolar II disorder as opposed to bipolar I disorder, where at least one manic episode is necessary for diagnosis. Therefore, the presence of both hypomanic episodes and major depressive episodes is what defines bipolar II disorder, making this the correct and most comprehensive choice.