19.01.1 Depression

Depression is described in the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV-TR) as a “mood disorder”, characterized by extreme or prolonged disturbance of mood, including sadness, lack of interest in or inability to experience pleasure, feelings of worthlessness and guilt, physical symptoms such as agitation, fatigue, insomnia and appetite changes, and often anxiety (American Psychiatric Association, 2004). In Australia, diagnosis of depression is made on the basis of a clinical interview using the DSM-IV-TR criteria. The symptoms of depression may last four months or more if left untreated. In many cases functioning returns to normal after this, however in some cases symptoms linger. Recurring depressive episodes can lead to major depressive disorder.