SPEAKERS

Background: Ayahuasca is a plant concoction containing N,N-dimethyltryptamine (DMT) and certain β-carboline alkaloids from South America. Previous research in naturalistic settings has suggested that ingestion of ayahuasca can improve mental health and well-being, however these studies were not placebo controlled and did not control for the possibility of expectation bias.

Aims: This naturalistic observational study was designed to assess whether mental health changes were produced by ayahuasca (matter), or by set (mind).

Methods: Assessments were made at pre and post-ayahuasca sessions in 30 participants of ayahuasca retreats of naturalistic, neo-shamanic origin hosted in The Netherlands, Spain and Germany. Participants were randomized into two treatment groups that ingested capsules containing ayahuasca (N = 14) or placebo (N = 16).

Results: Analysis revealed a main effect of Session on symptoms of depression, anxiety and stress. Compared to baseline, symptoms reduced in both groups after the ceremony, independent of treatment. There was a main Treatment x Session interaction on implicit emotional empathy, indicating that ayahuasca increased emotional empathy to negative stimuli.

Conclusion: The current findings suggest that subjective improvements in mental health of participants of naturalistic ayahuasca ceremonies can be driven by non-pharmacological factors such as expectations and intentions (mind-set). Yet, objective measures of empathy also revealed improvements that were solely observed after the pharmacological treatment with ayahuasca (matter). These findings stress the importance of placebo-controlled designs in psychedelic research and the need to further explore the contribution of non-pharmacological factors to the psychedelic experience.