Which disorder is characterized by mood swings that range from depressive lows to manic highs?

The disorder characterized by mood swings that fluctuate between depressive lows and manic highs is bipolar disorder. This condition entails significant mood changes that can impact an individual's daily functioning and overall quality of life. People with bipolar disorder experience episodes of mania or hypomania, where they may feel very elevated, energetic, or unusually irritable, followed by depressive episodes that feature feelings of sadness, hopelessness, or a lack of energy.

In contrast, major depressive disorder primarily involves cycles of depression without the manic episodes. Anxiety disorders include excessive worry or fear but do not typically include such dramatic mood swings. Schizophrenia is a chronic mental health condition that affects an individual’s thoughts, perception, and behavior but does not include the mood fluctuations indicative of bipolar disorder. Thus, bipolar disorder is the only option that explicitly describes the mood instability with both depressive and manic features, making it the correct answer.