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Hope in a Hallucinogen
It's known as Special K on the street and as an anesthetic in hospitals. And for about half of the treatment-resistant depression patients who received an IV ketamine infusion in studies, it was a miracle drug that reduced symptoms by 50 percent (or more) within a couple of hours. One of the key things ketamine does is work on the neurotransmitter glutamate, used by about 90 percent of the brain's synapses, says Chadi Abdallah, MD, assistant professor of psychiatry at Yale School of Medicine. "The chronic stress of depression weakens those synapses; ketamine sends the message that they need to be strengthened," he says.

Ketamine clinics around the country offer this off-label treatment even though long-term consequences are unknown. Some patients experience side effects like temporary nausea or an out-of-body sensation, says Carlos Zarate Jr., MD, chief of the experimental therapeutics and pathophysiology branch at the National Institute of Mental Health. He's working to develop a ketamine drug that won't cause negative side effects and plans to begin testing it by next year.