Psilocybin-induced alterations in EEG power, connectivity and network dynamics in healthy subjects: Correlations with subjective experience and implications for therapeutic applications

In this experimental pharmacology study, psilocybin appears to decrease alpha power, increase global connectivity, and enhance neural signal diversity, indicating a shift toward a more entropic and dynamically flexible brain state.

Background: Recent advancements in psychedelic research have highlighted psilocybin's potential therapeutic benefits for various mental disorders. Understanding its effects on brain function and identifying predictors of individual responses are essential for developing effective treatments.

Methods: This double-blind, randomized, crossover, and placebo-controlled study enrolled 25 healthy individuals (18 males, 7 females, average age 24.44 years). Participants underwent two sessions involving administration of either psilocybin (oral dose of 10-20 mg) or placebo. Ten-minute resting EEG recordings were taken at baseline and post-administration peaks, focusing on EEG power and connectivity in the default-mode network (DMN) and localized cortical networks in the frontal and parietal cortices. Additionally, we investigated whether baseline EEG features could predict subjective experiences during the psilocybin condition.

Results: Psilocybin significantly decreased EEG power in slow frequency bands (theta and alpha) and increased power in fast frequency bands (beta, gamma1, gamma2) compared to placebo. Connectivity analyses revealed increased connectivity in the DMN and localized parietal network under psilocybin. Subjective experiences, as measured by the Altered States of Consciousness Questionnaire, showed positive correlations with changes in EEG power and connectivity.

Conclusions: Psilocybin induces significant changes in brain function, characterized by altered EEG power and connectivity. These changes correlate strongly with subjective experiences, supporting psilocybin's potential for treating mental disorders. The predictive value of baseline EEG features for subjective alterations suggests that specific brain activity patterns may serve as biomarkers for tailoring psilocybin therapy in clinical settings. This study enhances our understanding of psilocybin's neurophysiological impacts and informs future therapeutic applications.

Ip CT, Olbrich S, de Bardeci M, Monn A, Ort A, Smallridge JW, Vollenweider F. Psilocybin-induced alterations in EEG power, connectivity and network dynamics in healthy subjects: Correlations with subjective experience and implications for therapeutic applications. Prog Neuropsychopharmacol Biol Psychiatry. 2026 Mar 20;145:111626. doi: 10.1016/j.pnpbp.2026.111626. Epub 2026 Jan 27. PMID: 41611012. Read Paper

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