Predicting and exploring ayahuasca effects: Perception, mind-wandering, and EEG oscillations
Natan Silva-Costa, Jéssica Andrade Pessoa, Kátia Cristina Andrade, Sérgio Mota-Rolim, Fernanda Palhano-Fontes, Dráulio Barros de Araújo, Isabel Wießner
Journal of Psychopharmacology December 4, 2025 DOI: 10.1177/02698811251389563 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized, double-blind, placebo-controlled, parallel-arm design Peer reviewed |
|---|---|
| Sample size | 50 |
| Population | Healthy volunteers |
| Intervention | Ayahuasca |
| Dose | 1 mL/kg |
| Topics | Ayahuasca Mysticism |
| Keywords | Interoception Electroencephalography Consciousness Cognitive psychology Neuroimaging Theta rhythm Brain mapping |
| Key points | Ayahuasca decreases global alpha oscillations and increases frontomedial delta and right posterior theta and beta; lower acute theta correlates with stronger mystical experiences, while lower baseline theta and beta predict greater interoception and positive emotionality. |
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.