Which of the following is a common symptom of major depressive disorder?

The correct answer, loss of interest in previously enjoyed activities, aligns with one of the hallmark symptoms of major depressive disorder (MDD). This symptom is known as anhedonia, where individuals experience a significant reduction in pleasure or interest in most activities, including those they once found enjoyable, such as hobbies, social interactions, or other daily activities. This is a critical feature of MDD and is often a major indicator that helps in the diagnosis of the disorder.

In contrast, increased energy levels, extreme confidence, and heightened enthusiasm are not characteristic symptoms of major depressive disorder. In fact, these symptoms may suggest a state of hypomania or mania, which are associated with mood disorders such as bipolar disorder rather than depression. Understanding these differences is essential for accurate diagnosis and effective treatment of mental health disorders.