Mood disorders are characterized by marked disturbances in emotional state, which affect thinking, physical symptoms, social relationships, and behavior. If mood is viewed as a continuum, mood disorders occur when a person experiences moods that lie at either extreme of the continuum. Mood disorders are of two basic types: unipolar or bipolar. People with unipolar disorders experience moods that are at the depressive end of the continuum. People with bipolar disorders experience moods that are at both ends of the continuum.
Mood disorders are generally episodic, which means they tend to come and go. The duration of the disturbed emotional state and the pattern of its occurrence determine how a mood disorder is diagnosed.
A person with dysthymic disorder experiences a depressed mood for a majority of days over at least two years.
Major depressive disorder is characterized by at least one major depressive episode. A major depressive episode is a period of at least two weeks in which a person experiences some or all of the following symptoms:
Major depressive disorder is much more common in women than in men.