Major Depressive Disorder

Definition: A mood disorder characterized by a depressed mood, a lack of interest in activities normally enjoyed, changes in weight and sleep, fatigue, feelings of worthlessness and guilt, difficulty concentrating and thoughts of death and suicide. If a person has experienced the majority of these symptoms for longer than a two-week period they may be diagnosed as having had a major depressive episode. If a person has had one or more major depressive episodes, has no history of mania, mixed episodes or hypomania and the symptoms are not due to another disorder, they may be diagnosed as having major depressive disorder.