Researchers investigated the effects of a single doses of 25 mg, 10 mg, or 1 mg (control) psilocybin over 12 weeks in 233 patients with treatment-resistant depression.
They were given the treatment in specialised rooms designed to provide a non-clinical and calming atmosphere where a specially trained therapist was available to provide psychological support.
The psychedelic effects of psilocybin last as long as eight hours, and once these had passed the participants were able to return home.
The results of the study, published in the New England Journal of Medicine, exhibited the result that participants reported a rapid and greater reduction on the Montgomery-Åsberg Depression Rating Scale (MADRS) three weeks after taking a single 25 mg.