Handbook of Mood DisordersAbout This Hardback A mood disorder is a group of conditions which are characterized by a disturbance in the person's mood. There are two primary types of mood disorders major depressive disorder and bipolar disorder. The major depressive disorder also known as major depression is a disorder in which a person has more than one major depressive incident. Individuals with a major depressive disorder are at increased risk for suicide. Bipolar disorder is