Psilocybin, a psychedelic drug derived from magic mushrooms, may be at least as effective as one of the leading antidepressants at treating depression, a study has found. The research provides further evidence in favour of licensing the therapy as a mental health treatment.
The researchers warn that people with depression should not self-medicate with psilocybin, as there is no evidence that the drug alone would provide any positive outcome. All tests have been carried out in a therapeutic environment under the supervision of trained professionals.
Previous research has shown that psilocybin has promise in alleviating treatment-resistant depression. In 2016, a team based at NYU Grossman School of Medicine published a study showing that cancer patients reported immediate, substantial, and sustained improvements in anxiety and depression following treatment with psilocybin combined with psychotherapy sessions. Then, in 2020, the same team followed up with the patients and found that 70 per cent had experienced long-term positive life changes following the therapy.
Now, a team based at the Centre for Psychedelic Research at Imperial College London has shown that the treatment could be at least as effective as escitalopram, a type of antidepressant known as a selective serotonin uptake inhibitor (SSRI).
The researchers studied 59 people with moderate-to-severe depression over the course of six weeks. Of those, 30 were given a high dose of psilocybin and a daily placebo, and the other 29 were given daily escitalopram and a “placebo” dose of psilocybin – a dose so low that it is unlikely to have any effect.
Both groups received two psilocybin dosing sessions, in which they received the drug and listened to a curated music playlist, while being guided by a psychological support team which included registered psychiatrists.
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"Context is crucial for these studies and all volunteers received therapy during and after their psilocybin sessions,” said Dr Rosalind Watts, clinical lead of the trial and formerly based at the Centre for Psychedelic Research. “Our team of therapists were on hand to offer full support through sometimes difficult emotional experiences."
All participants were assessed using a standard depression score which measures things like sleep, feelings of sadness, appetite and suicide ideation. The team did not find a statistically significant difference between the two groups in terms of how their depression scores changed over the six weeks, which implies that the psilocybin treatment worked as well as the antidepressant.
However, the team also looked at two additional measures: response and remission. Response is defined as when a person’s depression score reduces by at least 50 per cent; 70 per cent of people in the psilocybin group met this requirement, whereas only 48 per cent of the people in the antidepressant group did.
Remission of symptoms is classified as a depression score of 0-5 on a scale that goes up to 27. The team found that 57 per cent of the psilocybin group were in remission at the end of the study, compared to 28 per cent in the antidepressant group.
"These results comparing two doses of psilocybin therapy with 43 daily doses of one of the best performing SSRI antidepressants help contextualise psilocybin's promise as a potential mental health treatment. Remission rates were twice as high in the psilocybin group than the escitalopram group,” said Dr Robin Carhart-Harris, head of the Centre for Psychedelic Research at Imperial, who designed and led the study.
"One of the most important aspects of this work is that people can clearly see the promise of properly delivered psilocybin therapy by viewing it compared with a more familiar, established treatment in the same study. Psilocybin performed very favourably in this head-to-head."
The team acknowledge the limitations of this study, including the small number of participants, the short timescale and the lack of diversity among the patients. Nonetheless, they say that it is promising evidence in favour of the treatment.
"These findings provide further support for the growing evidence base that shows that in people with depression, psilocybin offers an alternative treatment to traditional antidepressants,” said Professor David Nutt, principal investigator on the study.
"In our study, psilocybin worked faster than escitalopram and was well tolerated, with a very different adverse effects profile. We look forward to further trials, which if positive should lead to psilocybin becoming a licensed medicine."
WARNING:Psychedelic drugs are a Class A drug according to UK law. Anyone caught in possession of such substances will face up to seven years in prison, an unlimited fine, or both. Info and support for those affected by substance abuse problems can be found atbit.ly/drug_support.
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