Experimental use of the drug called ketamine may be the beginning of a promising new class of antidepressants, which can relieve symptoms of major depression in hours instead of weeks, researchers found.

"It's exciting," Ron Duman, a psychiatrist and neurobiologist at Yale University, told NPR. "The hope is that this new information about ketamine is really going to provide a whole array of new targets that can be developed that ultimately provide a much better way of treating depression."

Research has looked at mice exposed to stress stimuli that damaged the synaptic connections between nerve cells, a condition that mimics depression in humans. A dose of ketamine reversed the damage and rejuvenated the connections within hours.

Researchers from Yale and the National Institute of Mental Health looked at 30 depressed patients who received doses of ketamine, tracking changes in their brainwave activity. They found that the drug appeared to produce an almost instantaneous response, caused by a burst of new connections to form between nerve cells in parts of the brain involved in mood and emotion, Forbes reported.

In any given year, 7 percent of adults suffer from major depression, and at least one in 10 youth will struggle with the disorder at some point during their teen years, TIME noted. About 20 percent of these cases will not respond to treatments currently available; for those that do, relief may not come for weeks, even months.

Ketamine, an FDA-approved anesthetic used in both veterinary and human medicine, also appears to reduce symptoms of suicidal thoughts and bipolar disorder, TIME reported. The new research is "arguably the most important discovery in half a century" of depression research, according to a review published in Science.

One drawback of the drug is that it produces out-of-body hallucinations, Forbes reported. "That side-effect has made it a popular drug in the club scene for a number of years." Researchers are working with derivatives of ketamine that retain the antidepressant attributes but do not cause excessive sedation or hallucinations.

However, the effects may not last, CBS noted. "According to the researchers behind the new study, the improvement in a patient may be evident within hours but the effects last only a week to 10 days."

Rachel Lowry is a reporter intern for the Deseret News. She has lived in London and is an English graduate from Brigham Young University. Contact her at rachel.lowry@gmail.com or visit www.rachellowry.blogspot.com.