Prevalence and therapeutic impact of adverse life event reexperiencing under ceremonial ayahuasca

As psychedelic therapies gain acceptance as tools for mental health care, important questions about safety and efficacy in relation to individual vulnerability factors remain incompletely addressed. One such factor is the potential for psychedelic experiences — particularly at moderate to high doses — to surface autobiographical memories of adverse life events, including trauma. Understanding whether such reexperiencing occurs, who is most susceptible, and what its psychological consequences are has direct relevance to screening, preparation, and support protocols in both ceremonial and clinical settings. This study examined the prevalence of adverse life event reexperiencing during ayahuasca ceremonies, identified demographic and clinical characteristics predictive of reexperiencing, and evaluated whether reexperiencing confers therapeutic benefit or poses psychological harm, using a prospective design in a naturalistic retreat sample.

Three hundred and fifty-one participants were recruited from three ayahuasca retreat centres across South and Central America, with the assistance of centre intake directors and the Heroic Hearts Project. Participants completed pre-ceremony questionnaires and post-ceremony follow-ups. Adverse life events were assessed using an adapted nine-item version of the Life Event Checklist for DSM-5 (LEC-5), covering categories including natural disaster, transportation accident, physical and sexual assault, illness or injury, loss of loved ones, and combat. Participants retrospectively reported whether specific adverse life events were reexperienced during ceremonies. Lifetime PTSD diagnosis was self-reported. Neuroticism was assessed at baseline and at post-ceremony and three-month follow-up. Ceremonial characteristics (intensity of experience, ayahuasca dose) were also recorded. Statistical analyses included logistic regression for predictors of reexperiencing and moderation analyses for the effect of reexperiencing on neuroticism change.

Of the valid sample of 339 participants, a substantial proportion reported reexperiencing adverse life events during ayahuasca ceremonies. Participants with a self-reported lifetime PTSD diagnosis reported all adverse life event types at significantly higher rates and showed significantly higher rates of ceremony-induced reexperiencing (X² = 6.83, p = 0.024) than those without a PTSD diagnosis. Women were significantly more likely than men to reexperience adverse life events during ceremonies, a difference driven substantially by women's higher rate of reexperiencing sexual assault. Across the full sample, a significant reduction in neuroticism was observed from baseline to post-ceremony and three-month follow-up. Critically, participants who reported reexperiencing adverse life events during ceremonies showed at least as large a reduction in neuroticism as those who did not, with moderation analyses indicating that reexperiencing did not attenuate — and may have enhanced — the ceremonial reduction in neuroticism. This pattern was consistent in both post-ceremony and three-month follow-up assessments.

The finding that adverse life event reexperiencing is relatively common during ayahuasca ceremonies — particularly among individuals with a PTSD history and women who have experienced sexual assault — has important implications for the screening, preparation, and facilitation practices of both ceremonial and clinical psychedelic programmes. The heightened vulnerability of these groups suggests that dedicated trauma-informed preparation and support are warranted. However, the observation that reexperiencing was associated with equivalent or greater reductions in neuroticism challenges a simplistic harm model. The data are more consistent with a therapeutic model in which psychedelic-facilitated recontact with adverse memories, in a supportive ceremonial context, may promote psychological processing and adjustment. This interpretation is consistent with qualitative accounts from ayahuasca users and with theoretical models of psychedelic therapy that emphasise the adaptive function of emotionally significant material arising during the experience. Limitations include the absence of a control condition and reliance on retrospective self-report of adverse life events.

This prospective study demonstrates that adverse life event reexperiencing during ayahuasca ceremonies is prevalent, particularly among women and those with a lifetime PTSD diagnosis, and that it appears to confer therapeutic benefit — evidenced by greater reductions in neuroticism — rather than psychological harm. These findings underscore the importance of trauma-informed screening and facilitation in psychedelic contexts and support the view that emotionally significant material arising during psychedelic ceremonies may play a constructive role in the psychological changes that follow.