A diagnosis of a Mood Disorder presupposes a disturbance of mood as the primary feature manifested by excessively high or low mood states that occur for a minimal duration of time. Associated symptoms are not attributed to any other physical or mental disor der. For the most part, DSM-IV retains the grouping of these disor ders under two basic categories: Depressive Disorders and Bipolar Disorders, with Bipolar Disorders further subdivided as Bipolar I or Bipolar II Disorders. Mood Disorder Due to a General Medical Condition and Substance-Induced Mood Disorder have been added to facilitate differential diagnosis based on etiology. Table 13.1 provides a listing of the Mood Disorders categories.