Small amounts of the drug ketamine can immediately relieve the symptoms of chronic depression, as well as those of treatment-resistant patients within a few hours, say Yale scientists.

After a decades' worth of research, experts from Yale School of Medicine suggest in the journal Science that the pediatric anesthetic repairs synaptic connections between brain cells that have been impaired by depression and stress.

This finding coincides with previous research from 2010 which showed that ketamine can rapidly relieve depression for people with treatment-resistant bipolar disorder.

The antidepressants in the pharmacies today take months to improve any symptoms of depression, while one out of every three patients receives no benefits at all.

  Ketamine, on the other hand, operates on an entirely different kind of neurotransmitter system.

A completely new way of treating depression and stress could come from understanding how this drug works in the brain. Tens of millions of chronically depressed individuals would be able to alleviate their symptoms faster than ever before.

"The rapid therapeutic response of ketamine in treatment-resistant patients is the biggest breakthrough in depression research in a half century," revealed Ronald Duman, the Elizabeth Mears and House Jameson Professor of Psychiatry and Professor of Neurobiology.

Scientists need to be conscious of every aspect of the drug, especially in terms of its limitations. For example, although symptoms are alleviated in a few short hours after the drug is taken, they return after 7 to 10 days.

Ketamine, if taken in large amounts, can result in short-term symptoms of psychosis, and is sometimes taken without medical reason as the recreational drug "Special K".

Duman and colleagues demonstrated that ketamine activates the release of the neurotransmitter glutamate, which stimulates the growth of synapses.

One dose of the drug can quickly fix the damage that has been done on these synaptic connections, researchers at Yale revealed.

The link between ketamine and its alleviating effects on depressive symptoms was first discovered by John Krystal, department chair of psychiatry at Yale, and Dennis Charney, dean of Mt. Sinai School of Medicine, who assisted in clinical trials of the drug while at the National Institute of Mental Health.

Although some drugs have been created that provide the same effects as ketamine, symptoms do not improve as fast. Further experiments are being conducted in order to duplicate not only the effects, but also the rapid response seen in ketamine.

Written by Sarah Glynn