Ayahuasca in the treatment of posttraumatic stress disorder: Mixed-methods case series evaluation in military combat veterans.

A mixed-methods case series of eight military veterans with moderate posttraumatic stress symptoms who participated in a three-day ayahuasca intervention in Central America found that most participants showed reliable or clinically significant reductions in PTSD symptoms after treatment, and most of those improvements were maintained at a three-month follow-up. Veterans also reported improvements in momentary PTSD symptoms and daily negative and positive affect. Perceived benefits included deep positive emotions, acceptance, and a sense of purpose, though adverse acute experiences were also reported. The study provides preliminary support for lasting benefits of a brief ayahuasca intervention on PTSD and mood symptoms in veterans.

Study at a glance

Abstract

[Correction Notice: An Erratum for this article was reported online in Psychological Trauma: Theory, Research, Practice, and Policy on Jul 25 2024 (see record 2025-07042-001). In the original article, there was an error in the calculations that led to the overstatement of the symptom severity of the veteran sample. Specifically, sum scores for the posttraumatic stress disorder (PTSD) symptom checklist (PCL-5) were scored using a 1-5 Likert scale rather than the appropriate 0-4 Likert scale. As a result, although it was stated that participants in the veteran sample exhibited clinical levels of PTSD based on the >33 PCL-5 threshold associated with a PTSD diagnosis, the levels actually reflected moderate posttraumatic stress symptoms. In addition, estimates of significantly reliable change in PCL-5 scores after an ayahuasca intervention (from 87.5% to 71.4%) were modified, and the threshold criteria for clinically significant changes (posttreatment scores <28) were removed because several participants met these criteria at baseline, thus impacting the interpretation of treatment outcomes.] Objective: Although ayahuasca-a plant-based psychedelic-is discussed as promising in the treatment of posttraumatic stress disorder (PTSD), evidence so far remains limited to retrospective case reports and qualitative surveys. No study to date has examined whether ayahuasca results in prospective and clinically meaningful changes in trauma symptoms across individuals with PTSD symptoms. To address this gap, we conducted a convergent mixed-methods case series study on eight military veterans with PTSD who participated in a 3-day ayahuasca intervention in Central America. Clinically meaningful changes from pre- to posttreatment and at a 3-month follow-up were assessed in three ways using: (a) PTSD checklist-5 (PCL-5); (b) experience sampling measurement of momentary PTSD and mood symptoms; and (c) an open-ended survey on perceived benefits. The majority (87.5%; 7/8) of participants demonstrated reliable and/or clinically significant changes in PCL-5 symptoms by posttreatment, which were maintained by 70% (5/7) of veterans by the 3-month follow-up. On average, veterans also reported significant improvements in momentary PTSD symptoms, as well as negative and positive affect in daily life posttreatment, with 63% (5/8) reporting moderate-to-large improvements in these domains. Broad themes characterizing the perceived benefits of ayahuasca included deep positive emotions, decentering/acceptance, and purpose in life; adverse acute experiences were, however, reported. This study provides preliminary support for the clinically meaningful and lasting benefits of a brief ayahuasca intervention on PTSD/mood symptoms in military veterans. (PsycInfo Database Record (c) 2024 APA, all rights reserved).