Which disorder is marked by episodes of both depression and mania?

Bipolar Disorder is characterized by episodes of both depression and mania. In this condition, individuals experience significant mood swings that include high-energy phases known as mania or hypomania, where they may feel overly happy, energetic, or irritable. These manic episodes can alternate with periods of depression, during which the person may feel hopeless, sad, or lose interest in activities they once enjoyed.

Understanding bipolar disorder's unique feature of alternating moods helps distinguish it from other mental health conditions. Major Depressive Disorder involves only depressive episodes, without mania. Generalized Anxiety Disorder is primarily characterized by excessive worry and anxiety, not mood swings. Post-Traumatic Stress Disorder involves flashbacks and anxiety following a traumatic event, but it does not include the manic or hypomanic states seen in bipolar disorder. Thus, the defining characteristic of experiencing both depressive and manic episodes solidifies Bipolar Disorder as the correct choice.