TO READ: An Antidepressant That Works in Hours
Research at the National Institute of Mental Health recently revealed that a single intravenous dose of a medication known as ketamine relieved depressive symptoms in as little as two hours in some people with treatment-resistant depression. Most antidepressants require four to eight weeks or more to be fully effective.

Ketamine, used in higher doses as an anesthetic in humans and animals, is only being used experimentally, in hopes that it will help scientists develop other new, faster-acting medications. The drug probably won't become widely used clinically because of potential side effects, including hallucinations and euphoria, at higher doses. Ketamine is thought to act quickly because it exerts its effect late in the series of biochemical actions that regulate mood, whereas current antidepressants target earlier steps in the series.

In the study, 71% of the treatment-resistant patients (who had tried an average of six medications without relief) felt improvement within one day of the treatment, and 29% of these people became nearly symptom-free during that first day. Thirty-five percent of those receiving ketamine still felt improvement a week later. None of the patients in the study had serious side effects.
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