While the scientists believe the results are valid, they concede that the study is not as robust as a standard, laboratory-based placebo-controlled clinical study. Since the participants sourced their own drugs, it is impossible to be sure what doses each ingested, and many of the participants were evidently familiar enough with the effects of the drug to guess whether they had taken a microdose of LSD or a placebo capsule.

James Rucker, a clinician scientist who runs the psychedelic trials group at King’s College London, and was not involved in the research, said: “This suggests that the perceived beneficial effects of microdosing psychedelics in this group are more likely to be a result of positive expectation than the capacity of the drug to induce a beneficial effect.”

Atticus Harris