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expert reaction to systematic review and meta-analysis of psilocybin for depression

A study published in the BMJ looks at psilocybin for treating depression symptoms. 


Prof David Nutt, The Edmond J Safra Chair and Head of the Centre for Neuropsychopharmacology, Division of Brain Sciences, Dept of Medicine, Imperial College London, said:

“This systematic review and meta-analysis confirms what smaller studies, such as our earlier work (Carhart-Harris 2016 and 2021) suggested – psilocybin looks rather good as an antidepressant. It is pleasing to see the field advancing as well as it is, especially given the mental health crisis facing most western countries.”


Dr Paul Keedwell, Consultant Psychiatrist and Fellow of the Royal College of Psychiatrists, said:

“This is a welcome review of the efficacy of a single dose of psilocybin in the treatment of depression. In general, the results are impressive, with rapid improvement in most, and large effect sizes.

“There are some concerns about expectation effects, because the majority of patients knew when they were getting the active condition, or the higher dose of the same drug. However, these concerns are tempered by the fact that improvements were maintained for up to 12 weeks in one study.

“Longer follow ups would be welcome, and there is more work to be done on optimal dosing. It seems that a strong psychedelic experience is needed to get the best results. Doses might need to be adjusted to body weight.

“The main disadvantage is that some patients find the psychedelic effects unpleasant, and care must be taken to ensure a calm environment for the treatment. Psychological preparation and debriefing, before and after dosing, respectively, are crucial.”



‘Efficacy of psilocybin for treating symptoms of depression: systematic review and meta-analysis’ by Athina-Marina Metaxa and Mike Clarke was published in The BMJ at 23:30 UK time on Wednesday 1 May.


DOI: 10.1136/bmj-2023-078084


Declared interests

Prof David Nutt: DJN via the Imperial College psychedelic research group has received support in kind from Compass Pathways and Usona for psilocybin research.

Dr Paul Keedwell: No conflict of interest


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