Why anesthetic ketamine produces a rapid antidepressant response.

Scientists are shedding new light on why the anesthetic ketamine produces a fast-acting antidepressant response in patients with treatment resistant depression. The drug's robust effect at low doses as a fast-acting antidepressant may have a use for high-risk patients in emergency departments.

"Ketamine produces a very sharp increase that immediately relives depression," said Dr. Lisa Monteggia, Associate Professor of Psychiatry at the University of Texas Southwestern Medical Center at Dallas.

Typical antidepressant medications are widely prescribed in the United States each year, but it often takes several weeks for them to relieve symptoms of depression. If patients do not respond within 12 weeks, physicians must prescribe a different antidepressant to produce a response.

Dr. Monteggia said, "Ketamine produces a fast-acting antidepressant effect, and we hope our investigation provides critical information to treat depression effectively soone. We now have a novel pathway to explore that may provide potential for the development of faster-acting and longer-lasting antidepressants."

The next step, she said, is to investigate further the short-term and long-term effects of the changes that occur when the brain cells communicate with each other. The study was funded by the National Institute of Mental Health, part of the National Institutes of Health (N.I.H.).

(Source: Nature, June 15, 2011.)