Microdosing psychedelics and its effect on creativity: Lessons learned from three double-blind placebo controlled longitudinal trials

Introduction: Microdosing refers to the repetitive administration of tiny doses of psychedelics (LSD, Psilocybin) over an extended period of time. This practice has been linked to alleged cognitive benefits, such as improved mood and creativity, potentiated by targeting serotonergic 5-HT2A receptors and facilitating cognitive flexibility. Nonetheless, in the absence of robust, quantitative and double-blind research on the effect of microdosing, such claims remain anecdotal.Methods: Here, our main aim was to quantitatively explore the effect of microdosing psychedelic truffles on two creativity tasks assumed to rely on separable processes: the Picture Concept Task assessing convergent thinking and the Alternative Uses Task assessing divergent thinking. We present results from 3 double-blind placebo-controlled longitudinal trials (of which one was pre-registered) conducted in a semi-naturalistic setting. Furthermore, we controlled for expectation and learning biases, and the data were mega-analyzed across trials with a pooled sample of 175 participants in order to maximize statistical power.Results: In the final analyses we found that active microdosing increased the ratio of original responses (originality/fluency), indicating higher quality of divergent answers in the active microdosing condition. The unadjusted originality score was significantly more pronounced in the active microdosing condition, but only when relative dosage (dose/weight of participants) was considered. These effects were present after controlling for expectation and demographic biases. No effects of active microdosing were found for convergent thinking or any other divergent-thinking score. The results suggest that the effects of truffle mirodosing are limited to divergent quality and are more subtle than initially anticipated. Our findings furthermore highlighted the importance of controlling for expectation biases, placebo effects, and prior psychedelic experience in microdosing practice and research.