Psychedelic Mushroom Chemical May Help Treat Depression

A new study found the drug temporarily relieved symptoms for some patients, but it needs to be tested in larger and longer trials, experts say

A photograph of a group of small, white psychedelic mushrooms.
Psilocybe cubensis mushrooms, a species of psychedelic mushrooms Jahi Chikwendiu / The Washington Post via Getty Images

The hallucinogenic chemical in ‘magic mushrooms,’ known as psilocybin, could relieve symptoms of depression, a new study finds.

Though participants experienced largely short-term improvements, the researchers hope their results will encourage further study and regulatory approval down the line.

Some 16 million U.S. adults suffer from depression each year, according to the Centers for Disease Control and Prevention. And around 30 percent of those who get treatment do not respond to it, writes CNN’s Sandee LaMotte.

The recent phase II trial recruited 233 adults with depression that had evaded other sorts of treatment. “These are folks who are not only severely depressed but also very frustrated, because they’ve tried so many different things,” Stewart Shankman, a clinical psychologist at Northwestern Medicine who was not involved with the study, tells NBC News’ Erika Edwards.

Participants received a single dose of psilocybin that was either 25 milligrams, 10 milligrams or 1 milligram. They were randomly assigned a dosage and neither they nor the researchers knew which one they had received until after the experiment. Two mental health specialists supervised patients through their six- to eight-hour trips, reports Lindsey Tanner of the Associated Press (AP).

Of the 79 participants that received the highest dosage, 37 percent showed substantial improvement in their depression and an additional 29 percent were in remission after three weeks.

However, the AP notes that studies of standard antidepressants have shown stronger results. And psilocybin's benefits didn’t always last in the long-term: After 12 weeks, the percentage of participants in the highest dosage group experiencing substantial improvements dropped to 20 percent, a level that was not statistically different compared to the other groups, per NBC News.

“This is not a spectacular response rate for a psychiatric treatment… and we would only expect this to worsen over a longer follow-up period,” Ravi Das, a psychopharmacologist at University College London in England who did not contribute to the study, tells CNN via email.

Still, to show such an improvement in people “who have not done well with existing treatments, and therefore are going to be much harder to treat,” is a benefit, Sandeep Nayak, a researcher at the Johns Hopkins University School of Medicine who was not involved with the study, tells NBC News.

Since participants attended three talk therapy sessions before receiving psilocybin, it’s unclear whether the drug or the therapy is contributing to the improvement, Steve Zalcman of the National Institute of Mental Health, who did not contribute to the study, says to NBC News.

Notably, 77 percent of trial participants experienced side effects, including headaches, nausea, fatigue and dizziness. A small number of people also experienced suicidal thoughts or self-harmed. Nobody in the trial attempted suicide.

“The numbers were fairly small, but this is something that will need to be taken carefully into account in any later-stage trials,” Kevin McConway, an applied statistician at The Open University in the U.K. who was not involved with the study, tells CNN.

The findings were published last week in the New England Journal of Medicine.

In the paper, the researchers write that “larger and longer trials, including comparison with existing treatments, are required to determine the efficacy and safety of psilocybin for this disorder.”

A phase III clinical trial to do just that is expected to start by the end of December, per NBC News. It will compare the 25-milligram dose to a placebo and repeat the phase II trial with an additional second psilocybin dose three weeks after the first.

COMPASS Pathways funded and helped run the study and is developing psilocybin for commercial use, per the AP.

Psilocybin might have other medical applications, such as aiding treatment for alcoholism. Researchers are also looking at whether the psychedelic chemical could treat other conditions, including chronic Lyme disease, Alzheimer’s and post-traumatic stress syndrome, according to NBC News.

The U.S. government classifies psilocybin as a controlled substance and has not approved it for medical use, according to the AP.

It remains unclear exactly how psilocybin might lessen symptoms of depression, and for that reason, some experts urge caution with this research. “I think we should be taking our foot off the gas a little bit and figure out exactly how [psychedelics] work in order to optimize it,” Philip Corlett, an experimental psychologist at Yale University, tells the AP.

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