Szigeti · eLife 2021 · self-blinded randomized placebo-controlled trial · n=191

Self-blinding citizen science to explore psychedelic microdosing.

Cited 198 times in the scientific literature.

Level 2 - randomized trial

Individual randomized placebo-controlled trial using a citizen-science self-blinding design

PubMed 33648632 · doi:10.7554/eLife.62878 · record verified 2026-08-26

What was done

A citizen-science self-blinding trial recruited regular psychedelic microdosers online who followed standardized instructions to set up their own placebo-controlled regimen without direct clinical supervision. A total of 191 participants completed the 4-week protocol comparing microdoses of self-sourced psychedelics against placebo capsules on cognitive function, psychological well-being, life satisfaction, acute states (emotional state, drug intensity, mood, energy, creativity), and post-acute anxiety.

What was found

The abstract reports no exact numerical values. Psychological outcomes improved significantly from baseline to the end of the 4-week dosing period in the microdosing group; however, the placebo group showed equivalent improvements, resulting in no statistically significant between-group differences. Small but statistically significant differences favoring microdoses were observed on acute scales (emotional state, drug intensity, mood, energy, creativity) and post-acute anxiety, but these were accounted for by participants correctly guessing their condition (breaking blind).

Why it matters

This study demonstrates that the widely reported anecdotal benefits of psychedelic microdosing on mood and cognition are largely attributable to expectancy and the placebo effect rather than pharmacological activity. It also validates a low-cost, self-blinding citizen science framework for testing substances with high public interest and strong prior expectations.

Limits

The study lacked clinical supervision: drug purity, substance type, and exact dosage were neither verified nor standardized. Self-administration at home introduced risk of unblinding, which accounted for the minor acute differences detected. The sample consisted of self-selected individuals already inclined toward microdosing, and all primary outcomes relied entirely on self-report. The abstract does not provide exact point estimates, confidence intervals, or p-values.

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