Abstract
Rationale: Previous studies with the serotonergic hallucinogens LSD and psilocybin showed that these drugs induced changes in personality traits, such as increases in Openness. However, results are inconsistent, and the effects of ayahuasca on personality were never investigated in a controlled trial.Objectives: To assess the effects of ayahuasca on personality in two randomized, placebo-controlled trials in healthy volunteers.Methods: Data from two parallel-group, randomized, placebo-controlled trials in healthy volunteers were included. In the first trial, 15 volunteers ingested ayahuasca or placebo, while in the second trial 15 volunteers received placebo+ayahuasca or cannabidiol (CBD)+ayahuasca. Personality was assessed with the NEO-Five Factor Inventory (NEO-FFI) at baseline and 21 days post-treatment.Results: There were significant differences between groups in baseline Openness scores, but not on day 21. A significant increase in Openness scores was observed in the placebo + ayahuasca group in study 2. No other within-group differences were observed for any other domain.Conclusions: Ayahuasca produced inconsistent effects on personality since it induced significant increase in Openness 21 days post-drug intake only in one of the trials. The absence of significant differences in the other ayahuasca groups could be due to small sample sizes and baseline differences among groups. The effects of ayahuasca and other serotonergic hallucinogens on personality should be further investigated in clinical samples.
Highlights
The relationship between personality and serotonergic hallucinogens such as lysergic acid diethylamide (LSD), psilocybin, and ayahuasca/dimethyltryptamine (DMT) is poorly understood [1]
15 volunteers were included in the final personality analysis of study 1
There were no significant effects of Time or in the Time x Group interaction in Neuroticism, Extraversion, Conscientiousness, and Agreeableness in both trials (p > 0.05)
Summary
The relationship between personality and serotonergic hallucinogens such as lysergic acid diethylamide (LSD), psilocybin, and ayahuasca/dimethyltryptamine (DMT) is poorly understood [1]. In a pooled analysis of two placebo-controlled trials involving administration of single and multiple doses of psilocybin to healthy volunteers a significant increase in the Openness to experience factor of the NEO-Five Factor Inventory (NEO-FFI) was observed 14 months following a high-dose psilocybin session [3]. A non-placebo-controlled trial with healthy volunteers corroborated the increase in Openness 6 months after psilocybin [5], but a recent placebo-controlled trial from the same group failed to find significant effects in Openness 1-month post-psilocybin, finding only a significant increase in Conscientiousness [6]. Regarding LSD, one placebo-controlled study in healthy volunteers found significant increases in Openness 2 weeks post-LSD [8] Another placebo-controlled trial did not find significant effects on Openness one and 12 months after LSD administration, finding only a significant increase in Conscientiousness [9]
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