Tardive dyskinesia in bipolar disorders: possible role of pineal melatonin

Several clinical studies have suggested that patients with affective disorders, 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 severity of TD. In most reported cases, depressive episodes are associated with exacerbation of TD, while manic episodes are accompanied by attenuation of TD. Current neurochemical hypotheses of TD do not explain adequately the relations of TD to depression or the mood dependent variations in the severity of TD. I propose that alterations in the secretory activity of pineal melatonin during manic and depressive episodes may explain better both the higher risk of TD in patients with affective disorders and the mood-dependent fluctuations in severity of TD. Consideration of pineal melatonin functions may further our understanding of the pathophysiology of TD in patients with affective disorders.