Psilocybin microdosing did not beat placebo on thinking or mood in two blinded trials

The question

Does taking very small, sub-perceptual doses of psilocybin (“microdosing”) actually improve attention, memory, social thinking or wellbeing more than a placebo?

What they did

Researchers ran two randomized, double-blind, placebo-controlled trials of microdosed psilocybin truffles in semi-naturalistic settings, meaning participants took the doses in everyday life rather than a lab. Neither the participants nor the researchers knew who received psilocybin and who received placebo. The team tracked people over time using a mix of performance tasks and questionnaires covering cognitive control, memory, social cognition, mood and subjective wellbeing, plus open-ended reports of the experience.

What they found

Microdosing did not significantly change behavioural or subjective measures compared with placebo. Some early signals appeared in social cognition, mood and self-reported cognitive flexibility, but these disappeared once the researchers corrected for testing many outcomes at once, a standard step to avoid chance findings. Most participants described their experience positively regardless of whether they got psilocybin or placebo. Negative bodily sensations were higher in the psilocybin group. Blinding held up: participants could not reliably tell which condition they were in.

The fine print

The abstract does not report how many people took part, the doses used, or how long the trials ran, so the ability to detect small effects is unclear. Participants were volunteers in semi-naturalistic settings rather than a controlled clinical population, and many outcomes were self-reported. Findings apply to short-term microdosing in this sample and may not generalize to people with diagnosed attention or mood conditions. This summary is based on the abstract only.

What it means

In two blinded trials, psilocybin microdosing did not improve thinking or emotional functioning beyond placebo, suggesting that much of the widely reported benefit may reflect expectation rather than the drug itself.

Evidence grade: Moderate. Two randomized, double-blind, placebo-controlled trials with successful blinding, but conducted in semi-naturalistic settings and the abstract does not report sample sizes or follow-up length.

This summary is based on the study’s published abstract.