Which disorder involves alternating periods of mania and depression?

Bipolar disorder is characterized by alternating periods of mania and depression. During manic episodes, individuals may experience an elevated mood, increased energy, and impulsive behavior, while depressive episodes involve feelings of sadness, hopelessness, and a lack of interest in activities. This cycling between the two mood states is a defining feature of bipolar disorder, distinguishing it from other mental health disorders.

In contrast, major depressive disorder primarily involves only depressive episodes without the manic phases, generalized anxiety disorder is characterized by persistent and excessive worry about various aspects of life, and obsessive-compulsive disorder features unwanted, repetitive thoughts (obsessions) and behaviors (compulsions) rather than mood fluctuations. Therefore, the distinctive pattern of alternating mood states is what makes bipolar disorder the correct answer.