Neurochemical Disorders I: Affective Disorders
‘Affect’ refers to mood and affective disorders comprise of both a pathological lowering (depression) and elevation (mania) of mood. Bipolar affective disorder (manic-depression) refers to an oscillation between depression and mania. These conditions are not simply characterized by mood changes, however, and depression may comprise a number of characteristic features.
Both depression and mania may be accompanied by features of psychosis (delusions and hallucinations; see Chapter 58). The nature of the psychosis tends to be mood-congruent: in depression, the patient may believe that he or she is guilty of something or hear voices that are critical and unpleasant. Mania may be accompanied by grandiose delusions.
This is a common and mania disorder with a lifetime prevalence that has been estimated to be as high as 15%, with women affected more than men (approximately 2:1). It can occur in response to adverse circumstances (reactive depression), as well as for no apparent circumstantial reason (endogenous depression), although often the distinction between these two different types of depression is not that clear-cut. In both cases the depression probably arises through a combination of genetic and environmental factors.