Tardive dyskinesia associated with depression in a bipolar patient: possible role of melatonin.

Several clinical studies have suggested that patients with affective disorder are at high risk for developing tardive dyskinesia (TD). An intriguing aspect of the relationship between TD and affective disorders involves mood dependent alterations in the severity of TD in bipolar patients. In most reported cases, depressive episodes have been reported to be associated with exacerbation of TD, while manic episodes were accompanied by attenuation of TD. Current neurochemical hypotheses of TD do not explain adequately the relationship of TD to depression or mania in bipolar patients. A patient with bipolar illness is presented in whom TD emerged concurrently with the onset of depression that developed during management of an acute manic episode. It is suggested that decline in melatonin secretion with onset of the depression was associated with the emergence of TD. Thus, the increased incidence and risk of TD in bipolar patients may in part be related to decreased melatonin secretion, while increased melatonin secretion during manic episodes may have protective effect against the development of TD.