Conventional antidepressant treatments generally require three to four weeks to become effective, thus the discovery of treatments with a more rapid onset is a major goal of biological psychiatry. The first drug found to produce rapid improvement in mood was the NMDA glutamate receptor antagonist, ketamine.

In a new issue of Biological Psychiatry, published by Elsevier, researchers from the National Institutes of Health report that another medication, scopolamine, also appears to produce replicable rapid improvement in mood. Scopolamine temporarily blocks the muscarinic cholinergic receptor, thought to be overactive in people suffering from depression.

Drs. Wayne Drevets and Maura Furey recruited outpatients with major depressive disorder who were randomly assigned to receive placebo and then scopolamine treatment, or vice versa, in a double-blinded design so that neither the researchers nor the patients knew which treatment they were receiving.

"Scopolamine was found to reduce symptoms of depression within three days of the first administration. In fact, participants reported that they experienced relief from their symptoms by the morning after the first administration of drug," explained Dr. Furey. "Moreover, one-half of participants experienced full symptom remission by the end of the treatment period. Finally, participants remained well during a subsequent placebo period, indicating that the antidepressant effects persist for at least two weeks in the absence of further treatment."

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