Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study
In an observational study of experienced Santo Daime ayahuasca users, acute pre-encoding administration of ayahuasca enhanced hippocampal-dependent episodic recollection, hit rates and overall memory accuracy while not altering familiarity-based memory or susceptibility to false memories. The authors propose beta-carboline activity and repeated prior use as possible explanations for this selective recollection enhancement, which contrasts with prior psychedelic findings.
Authors
- Johannes Ramaekers
- Nathalie Mason
- Jan Reckweg
Published
Abstract
Background
Ayahuasca is an Amazonian brew with 5-HT 2A -dependent psychedelic effects taken by religious groups globally. Recently, psychedelics have been shown to impair the formation of recollections (hippocampal-dependent episodic memory for specific details) and potentially distort memory while remembering. However, psychedelics spare or enhance the formation of familiarity-based memory (cortical-dependent feeling of knowing that a stimulus has been processed).
Aims
Given the growing literature on the plasticity-promoting effects of psychedelics, we investigated the acute impact of ayahuasca on recollection, familiarity, and false memory in an observational study of 24 Santo Daime members with >500 lifetime ayahuasca uses on average.
Methods
Participants completed a false memory task at baseline and after they consumed a self-selected dose of ayahuasca prepared by their church (average dose contained 3.36 and 170.64 mg of N,N -dimethyltryptamine and β-carbolines, respectively).
Results
Surprisingly, pre-encoding administration of ayahuasca enhanced hit rates, memory accuracy, and recollection but had no impact on familiarity or false memory. Although practice effects cannot be discounted, these memory enhancements were large and selective, as multiple measures of false memory and metamemory did not improve across testing sessions. β-carboline activity potentially accounted for this recollection enhancement that diverges from past psychedelic research. Although ayahuasca did not impact familiarity, these estimates were generally elevated across conditions compared to past work, alluding to a consequence of frequently driving cortical plasticity.
Conclusions
When encoding and retrieval took place under acute ayahuasca effects in experienced ayahuasca users, susceptibility to memory distortions did not increase, potentially owing to enhancements in memory accuracy.
Research Summary of 'Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study'
Introduction
Doss and colleagues situate this study within growing interest in how psychedelics affect episodic memory, that is, the conscious re-experiencing of past events. They note ayahuasca is a brew containing DMT (from Psychotria viridis) and β-carbolines (from Banisteriopsis caapi); β-carbolines render DMT orally active by inhibiting monoamine oxidase A (MAO-A) and have their own psychoactive properties. Previous human and animal work shows psychedelics and other psychoactive drugs can differentially affect memory phases (encoding, consolidation, retrieval) and distinct memory processes, especially recollection (hippocampal-dependent retrieval of contextual detail) and familiarity (a cortical-dependent sense that a stimulus has been encountered). Those earlier findings are mixed: pre-encoding psilocybin and MDMA often impair recollection, whereas familiarity can be spared or even enhanced, and drugs administered around retrieval have been associated with increased false memories for some compounds. This observational study aimed to characterise how ayahuasca acutely influences true and false episodic memory, recollection versus familiarity, and metamemory in a sample of experienced Santo Daime members. The investigators tested participants both sober and while acutely intoxicated by a self-selected ceremonial ayahuasca batch, using a three-phase false-memory paradigm (encoding, misinformation, retrieval) designed to probe suggestion-driven distortions as well as objective measures of recollection and familiarity. They emphasised examining memory when drug effects spanned encoding, misinformation, and retrieval, a situation ecologically relevant to frequent ceremonial use but rarely modelled experimentally.
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Study Details
- Study Typeindividual
- Journal
- Compounds
- Authors
- APA Citation
Doss, M. K., Kloft, L., Mason, N. L., Mallaroni, P., Reckweg, J. T., van Oorsouw, K., Tupper, N., Otgaar, H., & Ramaekers, J. G. (2025). Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study. Journal of Psychopharmacology, 39(4), 339-349. https://doi.org/10.1177/02698811241301216
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