How long must symptoms persist to diagnose major depressive disorder?

To diagnose major depressive disorder, symptoms must persist for at least two weeks. This period is critical because it ensures that the symptoms are not just part of a temporary mood fluctuation but are instead indicative of a more serious and ongoing depressive episode. The diagnostic criteria for major depressive disorder, as outlined in the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition), specify that individuals must experience a depressed mood or loss of interest or pleasure in nearly all activities, along with several other symptoms, over this two-week duration. This timeframe helps differentiate major depressive disorder from other mood disturbances, such as a brief adjustment disorder or situational depression, where symptoms may resolve more quickly. Therefore, the requirement of two weeks is essential for a thorough and accurate diagnosis, providing the clinician with a clearer understanding of the persistence and severity of the depressive symptoms.