Malin Uthaug

Malin Uthaug, PhD candidate

Maastricht University

Mind or matter? A placebo-controlled study of the effects of ayahuasca ingestion on mental health of participants in a naturalistic, neo-shamanic setting.


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.


Malin Vedøy Uthaug has a background in psychology and is currently a PhD candidate at the department of Neuropsychology and Psychopharmacology (FPN) at Maastricht University. Her doctoral research, supervised by Dr. Jan Ramaekers and Dr. Jordi Riba, centres around the investigation of the effects of Ayahuasca ingested in a naturalistic setting on affect and cognition, in addition to extensive work on the effects of 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) in humans. Outside of her thesis work, Malin is also conducting research on mescaline and Holotropic Breathwork, is interested in trauma resolution and Non-Ordinary State Psychotherapy (NOSP), and finally, she is also one of the co-founders of the Norwegian Association for Psychedelic Studies.



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