What describes major depressive disorder (MDD)?

Major depressive disorder (MDD) is characterized by the presence of one or more major depressive episodes lasting at least two weeks. During these episodes, individuals experience a persistently low mood and may also have a range of symptoms, such as changes in appetite, sleep disturbances, fatigue, feelings of worthlessness, or recurrent thoughts of death or suicide. The duration of at least 14 days is crucial for a diagnosis, as it helps differentiate MDD from transient mood fluctuations or more temporary depressive states.

While other options present statements that may relate to different aspects of depressive disorders or misconceptions, they do not accurately capture the key features of MDD. For instance, symptoms of MDD do not simply fluctuate every few months nor is it exclusive to childhood; it can occur at any age. Also, while exercise can be beneficial for mood improvement in some individuals, it does not guarantee a positive response in everyone suffering from MDD. Therefore, the correct choice reflects a core diagnostic criterion that is essential in understanding how major depressive disorder is defined and diagnosed.