Mood refers to a subjective psychological experience that is typically longer lasting and more diffuse or pervasive than an emotion, though moods and emotions are related. The category “mood disorders” generally refers to the depressive disorders and the bipolar disorders—now separate categories in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), though the International Classification of Diseases, 10th Revision, continues to use the category “Mood (Affective) Disorders.” Certainly, many psychological disorders (even those not in these categories) involve changes in mood, and the depressive and bipolar disorders include many symptoms that are cognitive, physiological, or behavioral in nature, in addition to mood symptoms. What leads to these disorders being grouped together is the predominance of the mood symptoms, as the changes in ...