Translational Psychiatry
August 2, 2022
Federico Cavanna, Stephanie Müller, Laura Alethia de la Fuente et al.
130 citations
A double-blind placebo-controlled trial tested the effects of a low (0.5 g) dose of dried psilocybin mushrooms on 34 individuals beginning a microdosing protocol. The active dose produced more intense acute subjective effects than placebo, but only among participants who correctly guessed their condition. These effects coincided with reduced EEG theta-band power and preserved Lempel-Ziv broadband signal complexity. No evidence was found for enhanced well-being, creativity, or cognitive function; instead, small changes toward cognitive impairment appeared. The findings suggest that expectation, not the drug itself, accounts for many anecdotal benefits attributed to psilocybin microdosing.
bioRxiv (Cold Spring Harbor Laboratory)
December 7, 2021
Federico Cavanna, Stephanie Müller, Laura Alethia de la Fuente et al.
8 citations
preprint
A double-blind placebo-controlled trial tested the effects of a low (0.5 g) sub-hallucinogenic dose of dried psilocybin mushrooms in 34 individuals planning to microdose. Acute subjective effects were significantly stronger with the active dose than with placebo, possibly due to unblinding. For other measures—including creativity, perception, cognition, and brain activity—the results were null or showed a trend toward cognitive impairment and, in electroencephalography, reduced theta band spectral power. These findings suggest that expectation effects may account for some of the anecdotal benefits people report from microdosing psilocybin.
bioRxiv (Cold Spring Harbor Laboratory)
November 1, 2023
Stephanie Müller, Federico Cavanna, L. de la Fuente et al.
3 citations
preprint
High doses of psilocybin mushrooms cause people to explore paintings with more local, less random eye movements, making their gaze patterns less entropic. Participants also reported stronger emotional responses and a greater state of flow under the high dose. These effects are consistent with psilocybin altering the perception of low-level visual features like textures, shapes, and colors. The findings demonstrate that eye-tracking under naturalistic conditions can objectively measure psychedelic-induced perceptual changes, supporting greater ecological validity.
bioRxiv Preprint Server
December 19, 2024
Evan Lewis-Healey, Carla Pallavicini, Federico Cavanna et al.
1 citation
preprint
A dose of the fast-acting psychedelic DMT rapidly reorganizes conscious experience and brain dynamics, but the link between neural complexity and subjective effects is weaker than previously thought. Nineteen participants received 20 mg or 40 mg of DMT in two sessions. The higher dose produced more extreme visual hallucinations and emotionally intense experiences. Contrary to earlier claims, Lempel-Ziv complexity—a measure of neural signal diversity—was the least strongly associated neural marker of the psychedelic state. The findings suggest the relationship between neural complexity and phenomenology during psychedelic experiences is less clear than originally hypothesized.
bioRxiv (Cold Spring Harbor Laboratory)
February 22, 2022
Camila Sanz, Federico Cavanna, Stephanie Müller et al.
1 citation
preprint
Low doses of psilocybin (microdoses) can be detected in natural speech. In a double-blind, placebo-controlled experiment, participants given 0.5 g of psilocybin mushrooms showed significant differences in verbosity and sentiment scores compared to placebo, though semantic variability did not differ. Machine learning classifiers using these speech metrics distinguished between the psilocybin and placebo conditions with high accuracy (AUC≈0.8). These findings suggest that unconstrained natural language may serve as a practical, low-cost tool for monitoring microdosing effects, addressing limitations of existing questionnaires designed for larger psychedelic doses.
Apollo (University of Cambridge)
December 30, 2025
Evan Lewis-Healey, Carla Pallavicini, Federico Cavanna et al.
A dose of the fast-acting psychedelic drug DMT rapidly reorganizes both conscious experience and brain activity. In a blinded, counterbalanced study, 19 participants received either 20 mg or 40 mg of freebase DMT. The higher dose caused more extreme visual hallucinations and emotionally intense experiences. Electroencephalography showed that changes in alpha brainwave power and a measure of signal irregularity (permutation entropy) were most strongly linked to moment-by-moment changes in subjective experience. Surprisingly, a measure of neural signal complexity (Lempel-Ziv complexity), previously thought to be a robust marker of psychedelic states, showed the weakest link to experience. This suggests the connection between brain complexity and conscious experience during psychedelic states is less straightforward than previously assumed.