Predicting and exploring ayahuasca effects: Perception, mind-wandering, and EEG oscillations
In a double-blind, placebo-controlled trial of 50 volunteers, ayahuasca produced robust perceptual, emotional and mystical experiences alongside EEG changes (notably reduced global alpha and increased frontomedial delta and right-posterior theta/beta), with acute lower theta linked to stronger mystical effects and baseline theta and beta oscillations predicting interoceptive and emotional responses.
Authors
- Isabel Wießner
Published
Abstract
Background
Psychedelics induce profound changes in perception and thinking; however, little is known about the neural mechanisms and prediction of these effects.
Aims
Investigating ayahuasca-induced experiences, mind-wandering, and electroencephalogram (EEG) oscillations, beyond the prediction of subjective experiences by baseline EEG.
Methods
In a randomised, double-blind, placebo-controlled, parallel-arm design, 50 healthy volunteers received 1 mL/kg of ayahuasca or placebo. We measured subjective psychedelic experiences (Hallucinogen Rating Scale (HRS), Mystical Experience Questionnaire (MEQ)) and mind-wandering (Amsterdam Resting-State Questionnaire (ARSQ)). EEG signals were assessed before administration (+0h), and 2 hours (+2h) and 4 hours (+4h) post-administration. Relationships between subjective and EEG effects were examined.
Results
Ayahuasca, compared to placebo, induced subjective experiences, including changed perception, cognition, emotion (HRS), mystical experiences (MEQ), and visual, discontinuous, and content-laden thinking (ARSQ). Ayahuasca, compared to placebo, changed EEG oscillations, including decreased global alpha as well as increased frontomedial delta and right posterior theta and beta. Under ayahuasca, lower theta correlated with higher mystical experiences (MEQ) and higher alpha correlated with lower Thoughts about Nothing (ARSQ). Baseline global EEG oscillations predicted ayahuasca-induced experiences, with lower theta linked to higher interoception (HRS Heart Beat, HRS Rush, ARSQ Somatic Awareness) and lower beta linked to higher positive emotionality (HRS Happy).
Conclusion
Ayahuasca induced consciousness alterations, visual, bodily, emotional, and mystical experiences, chaotic and meaningful mind-wandering, and decreased especially alpha. While acute theta seems inversely related to mystical experiences, baseline theta and beta seem to inversely predict interoception and emotionality.
Research Summary of 'Predicting and exploring ayahuasca effects: Perception, mind-wandering, and EEG oscillations'
Introduction
Ayahuasca is a DMT-containing traditional Amazonian psychedelic that is increasingly used in religious, shamanic and therapeutic settings. Earlier research had shown that psychedelics can strongly alter perception, emotion, cognition and mystical-type experience, and EEG studies had repeatedly found broad frequency changes, especially reduced alpha power. However, ayahuasca’s effects on mind-wandering had not been explored, and the predictive value of baseline EEG for acute ayahuasca experiences remained unclear. The paper also notes that relationships between mind-wandering and EEG under psychedelics were largely unknown. Silva-Costa and colleagues therefore set out to examine how ayahuasca affects subjective psychedelic experience, mind-wandering and EEG oscillations, and whether baseline EEG activity can predict acute subjective responses. They also aimed to relate EEG changes to the reported experiences, with a particular focus on perception, mystical effects and internally directed thinking. The study is presented as the first to investigate ayahuasca-related mind-wandering together with neural correlates and EEG-based prediction of experience in a controlled laboratory design.
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Study Details
- Study Typeindividual
- Journal
- Compound
- Topics
- Author
- APA Citation
Silva-Costa, N., Pessoa, J. A., Andrade, K. C., Mota-Rolim, S., Palhano-Fontes, F., Araujo, D. B., & Wießner, I. (2025). Predicting and exploring ayahuasca effects: Perception, mind-wandering, and EEG oscillations. Journal of Psychopharmacology. https://doi.org/10.1177/02698811251389563
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