Ketamine effectively treats severe depression in Australian clinical trial

Treating severe depression with ketamine Dr. Jennifer Phillips with The Royal explains how a new treatment can help with severe depression.

Ketamine can effectively treat severe depression, according to a new study.

Published Friday in the British Journal of Psychiatry, the study found that more than one in five patients with treatment-resistant depression saw symptoms disappear after receiving ketamine injections in a clinical trial, while one third reported their symptoms improved by at least 50 per cent.

"We found that in this trial, ketamine was clearly better than the placebo – with 20 per cent reporting they no longer had clinical depression compared with only two per cent in the placebo group," lead author Colleen Loo said in a news release. "This is a huge and very obvious difference and brings definitive evidence to the field which only had past smaller trials that compared ketamine with placebo."

Loo, a clinical psychiatrist and professor at Australia's University of New South Wales Sydney, calls ketamine a "powerful treatment" for depression.

"For people with treatment-resistant depression – so those who have not benefitted from different modes of talk-therapy, commonly prescribed antidepressants, or electroconvulsive therapy – 20 per cent remission is actually quite good," Loo said.

Primarily used as an anesthetic by veterinarians, ketamine is also used to a lesser extent in human medicine and as a recreational drug for its dissociative effects.

In the study, researchers tracked 179 patients with treatment-resistant depression. Participants were either given two weekly injections of ketamine or a placebo, and were then asked to assess their mood at the end of the month-long trial and again a month later. In the trial, a surgical sedative was chosen as the placebo instead of typical saline solution in order to simulate ketamine's effects.

"Because there are no subjective effects from the saline, in previous studies it became obvious which people were receiving the ketamine and which people received placebo," Loo explained.

The study builds on a growing body of evidence that psychoactive drugs like ketamine and psilocybin mushrooms can be effective treatments for depression.

Canada approved a nasal spray version of ketamine for depression in May 2020. The Australian study used a generic version of the drug that is typically a fraction of the cost.

"And if you consider that many of these people might spend many months in hospital, or be unable to work and are often quite suicidal, it’s quite cost effective when you see how incredibly quickly and powerfully it works," Loo said. "We’ve seen people go back to work, or study, or leave hospital because of this treatment in a matter of weeks."