Assessment of heart rate variability and psychometric parameters in experienced Ayahuasca users

Background: Ayahuasca (Aya) is a psychedelic brew of Amazon origin produced mainly from two plants (Psychotria viridis and Banisteriopsis caapi), containing N, N-Dimethyltryptamine (DMT), and beta-carbolines which affect the serotonergic system. The use of Aya has expanded worldwide, but there are few studies on its regular use in behavioral and physiological aspects. We aim to investigate autonomic nervous system and behavioral differences in volunteers who use Ayahuasca regularly compared to a control group that does not use it. Methods: We recruited 20 experienced users and 20 matched control volunteers. We evaluated the Heart Rate Variability (HRV) parameters and also psychometric symptoms of resilience, emotional dysregulation, mindfulness facets. Results: Aya group scored higher for mindfulness (p<0.01) and resilience (p=0.03), while they scored lower for some constructs of the emotional dysregulation questionnaire (p<0.01) when compared to control group. Aya group also had higher values in HRV parameters related to sympathetic-vagal modulation (LF p=0.04), LF/HF p=0.03 and SD1/SD2 p=0.03) and lower values for the high frequency parameter (HF p=0.02) that reflects parasympathetic modulation of HRV. Regarding cardiovascular risk, the Aya group had higher values (p=0.01) than the control group in DFAα1 parameter, although both remained outside the cardiovascular risk range. Conclusions: This study confirmed the neurophysiological and behavioral differences between experienced Aya group and a control. The psychometric results support previous studies exhibiting better indices of emotional regulation, resilience and mindfulness of experienced Aya users, reflecting improved mental health conditions. Despite presenting lower parasympathetic activity which may reflect stressful or mental health conditions, the Aya subjects did not show signs of cardiovascular risk and showed higher sympathovagal modulation which may be related to autonomic flexibility.