The presence of _____________ differentiates bipolar disorder from unipolar disorder.

The presence of mania is a key factor that differentiates bipolar disorder from unipolar disorder. In bipolar disorder, individuals experience episodes of both depressive states and distinct manic episodes. Mania is characterized by elevated mood, increased energy, and significant changes in behavior that can lead to impaired functioning or necessitate hospitalization. These manic episodes are not present in unipolar disorder, which consists solely of depressive episodes.

While hypomania, a milder form of mania, is also associated with bipolar disorder, the defining feature that can clearly differentiate it is the presence of full-blown manic episodes. Sadness and delusions can occur in various mood disorders, but they do not provide the specific distinction needed to differentiate between bipolar and unipolar disorders. Thus, the correct identification of mania as a component of bipolar disorder is crucial in understanding and diagnosing these mood disorders effectively.