Journal of Psychopharmacology
December 17, 2021
Josephine Marschall, George Fejer, Pascal Lempe et al.
69 citations
In a double-blind, placebo-controlled, within-subject crossover study, psilocybin microdosing (a sub-hallucinogenic dose taken every third day) did not alter emotion processing, symptoms of anxiety or depression, or self-reported interoceptive awareness compared with placebo. Exploratory analyses showed that symptoms of depression and stress were significantly reduced in the first block compared with baseline, but participants broke blind in the second block, and there was no effect of expectations. The authors call for further research in a substance-naïve population with clinical-range anxiety and depressive symptoms to substantiate potential beneficial effects.
Psychopharmacology
April 30, 2021
Michiel van Elk, George Fejer, Pascal Lempe et al.
53 citations
People who take small, non-hallucinogenic doses of psilocybin (microdosing) report feeling more awe when watching videos of funny animals and moving objects compared to when they take a placebo. However, about two-thirds of participants correctly guessed whether they had received psilocybin or placebo, suggesting that expectancy effects—rather than the drug itself—may explain the subjective benefits of microdosing. The study used a double-blind, placebo-controlled crossover design with a microdosing workshop and lab visits over several weeks.
June 14, 2021
Luisa Prochazkova, Michiel van Elk, Josephine Marschall et al.
4 citations
preprint
Microdosing psychedelic truffles increased the quality of divergent thinking, measured as the ratio of original responses to total responses on the Alternative Uses Task, in a pooled analysis of three double-blind placebo-controlled trials with 175 participants. The unadjusted originality score was significantly higher only when relative dosage (dose per body weight) was considered. No effects were found on convergent thinking or other divergent-thinking scores. The effects were subtle and persisted after controlling for expectation and demographic biases. The findings underscore the importance of controlling for placebo effects and prior psychedelic experience in microdosing research.
Neuropharmacology
October 17, 2025
Luisa Prochazkova, Josephine Marschall, Dominique P. Lippelt et al.
3 citations
Microdosing psilocybin truffles does not reliably enhance cognitive or emotional functioning beyond a placebo. In two randomized, double-blind, placebo-controlled trials conducted in semi-naturalistic settings, microdosing did not significantly affect behavioral or subjective measures compared to placebo. Some initial effects on social cognition, mood, and self-reported cognitive flexibility were observed but did not remain significant after correcting for multiple comparisons. Participants predominantly reported positive subjective experiences regardless of condition, though negative bodily feelings were enhanced in the active condition. Participants remained effectively blinded throughout the trials.
Neuropharmacology
November 2, 2025
Luisa Prochazkova, Josephine Marschall, Michiel van Elk et al.
2 citations
Microdosing psilocybin from truffles modestly improved the quality of divergent thinking—specifically the ratio of original responses to total responses—in a pooled analysis of three double-blind, placebo-controlled trials with 171 participants. The effect on unadjusted originality was significant only when dosage relative to body weight was considered, and it remained after controlling for dose guess and demographic biases. No effects were found on other measures of divergent thinking or on convergent thinking. The findings underscore the need to account for placebo effects and prior psychedelic experience when evaluating microdosing claims.