Serendipity strikes again: scopolamine as an antidepressant agent in bipolar depressed patients.

The adrenergic-cholinergic balance hypothesis of mania and depression suggests that depression may be due to an over-activity or a hypersensitivity to central acetylcholine. From this hypothesis, it is logical that scopolamine, a centrally acting antimuscarinic agent, would be useful as an antidepressant. Authors, working at the Intramural Program at NIMH in Bethesda Maryland have shown that intravenous scopolamine is a rapidly acting, effective antidepressant and have than replicated this finding. They now report that this antidepressant effect occurs in bipolar, as well as unipolar depressed patients. The clinical and theoretical implications of this finding for difficult to treat bipolar depressed patients is considerable, and the finding is in need of independent replication.