Scientists map the brain waves behind the intense effects of ayahuasca

Ayahuasca alters EEG brain-wave patterns in ways that track how intensely people report mystical experiences, vivid perceptions, and emotional changes. In a randomized, double-blind, placebo-controlled study of 50 ayahuasca-naive healthy adults, researchers recorded EEG before dosing and again two and four hours after ingestion while participants reported visual imagery, emotions, mystical sensations, synesthesia-like effects, and patterns of spontaneous thoughts. Brain measures linked to the experience included a widespread decrease in alpha waves and localized slow-delta increases, alongside changes in theta and beta activity. Lower baseline theta activity predicted stronger feelings of mystical unity and more interoception during the trip, while baseline beta activity correlated with more positive emotions. The authors note key limitations, including the clinical setting lacking traditional ritual context and delays in measuring mind-wandering reports.