Effects of Ayahuasca on the Recognition of Facial Expressions of Emotions in Naive Healthy Volunteers: A Pilot, Proof-of-Concept, Randomized Controlled Trial
In a pilot randomised controlled trial of 22 healthy volunteers, a single dose of ayahuasca produced no significant acute or prolonged change in recognition of facial expressions of emotion compared with placebo. The brew was generally well tolerated but showed time-dependent alkaloid degradation (notably DMT), which—alongside dosing, learning effects and sample characteristics—may account for the negative finding and indicates future trials should ensure alkaloid stability.
Authors
- Rafael dos Santos
- Guilherme Rossi
- Mariana Yonamine
Published
Abstract
Background
The recognition of emotions in facial expressions (REFE) is a core aspect of social cognition. Previous studies with the serotonergic hallucinogens lysergic acid diethylamide and psilocybin showed that these drugs reduced the recognition of negative (fear) faces in healthy volunteers. This trial assessed the acute and prolonged effects of a single dose of ayahuasca on the REFE.
Methods
Twenty-two healthy volunteers participated in a pilot, proof-of-concept, randomized trial. Study variables included a REFE task performed before and 4 hours after drug intake, subjective effects (self-reports/observer impressions), tolerability measures (cardiovascular measures, self-reports), and brain-derived neurotrophic factor plasma levels. The REFE task was applied again 1, 7, 14, and 21 days and 3 months after drug intake. Stability of ayahuasca alkaloids during the study was also assessed (room temperature, 18 months).
Findings
Compared with placebo, ayahuasca did not modify the REFE. No significant effects were observed on cardiovascular measures and brain-derived neurotrophic factor levels. Volunteers reported visual effects, tranquility/relaxation, and well-being, with few reports of transient anxiety/confusion. Ayahuasca was well tolerated, producing mainly nausea, gastrointestinal discomfort, and vomiting. A significant time-dependent deterioration of alkaloids was observed, especially for dimethyltryptamine.
Conclusions
Absence of significant effects on the REFE task could be due to lack of effects of ayahuasca (at the doses used), alkaloid degradation, learning effects, and the high educational level of the sample. Further trials with different samples are needed to better understand the effects of ayahuasca and other serotonergic hallucinogens on the REFE. Future trials should improve methods to guarantee the stability of ayahuasca alkaloids.
Research Summary of 'Effects of Ayahuasca on the Recognition of Facial Expressions of Emotions in Naive Healthy Volunteers: A Pilot, Proof-of-Concept, Randomized Controlled Trial'
Introduction
Recognition of emotions in facial expressions (REFE) is central to social cognition and has been used to probe the effects of serotonergic hallucinogens on emotional processing. Earlier experimental work with LSD and psilocybin reported mixed findings, with some studies showing reduced recognition of negative emotions (notably fear) and others showing no effect or variable effects on reaction time. To date, the effects of ayahuasca, a traditionally used brew containing N,N-dimethyltryptamine (DMT) and β-carbolines, on REFE had not been assessed in controlled trials. Mendes Rocha and colleagues designed a pilot, proof-of-concept, randomised, double-blind, placebo-controlled, parallel-group trial to test whether a single dose of ayahuasca modifies REFE in healthy, ayahuasca-naive volunteers. Secondary objectives included characterising subjective effects, tolerability (cardiovascular measures and adverse events), plasma brain-derived neurotrophic factor (BDNF) as a proxy for neuroplasticity, and the chemical stability of ayahuasca alkaloids over the 18-month study period.
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Study Details
- Study Typeindividual
- Journal
- Compounds
- Topics
- Authors
- APA Citation
Rocha, J. M., Rossi, G. N., de Lima Osório, F., Bouso, J. C., de Oliveira Silveira, G., Yonamine, M., Campos, A. C., Bertozi, G., Cecílio Hallak, J. E., & dos Santos, R. G. (2021). Effects of Ayahuasca on the Recognition of Facial Expressions of Emotions in Naive Healthy Volunteers: A Pilot, Proof-of-Concept, Randomized Controlled Trial. Journal of Clinical Psychopharmacology, 41(3), 267-274. https://doi.org/10.1097/jcp.0000000000001396
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