A prominent and persistent disturbance in mood characterized by either or both of the following: markedly diminished interest or pleasure in all, or almost all, activities; and elevated, expansive, or irritable mood. The clinical and laboratory findings are consistent with attributing the cause to a direct physiological consequence of the general medical condition. The condition is not better accounted for by another mental disorder. The disturbance does not occur exclusively during the course of a delirium. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.