Ayahuasca-assisted therapy for addiction: results from a preliminary observational study in Canada

Ayahuasca is an Amazonian psychotropic brew combining Banisteriopsis caapi (harmala alkaloids) and Psychotria viridis (dimethyltryptamine, DMT) that produces extended altered states of consciousness. Earlier observational work among members of Brazilian ayahuasca churches and in therapeutic communities such as Takiwasi and IDEAA has suggested potential salutogenic effects, including lower substance use and improvements in psychosocial functioning. However, those studies largely involve people who are regular members of religious communities or treatment centres, and have not provided rigorous evidence that the brew itself, as opposed to the broader communal or therapeutic context, produces benefits for substance dependence. There is therefore uncertainty about generalisability to other populations and about which elements of ritualised ayahuasca use are most relevant to recovery from addiction. This study, conducted with a coastal First Nations band in rural British Columbia, set out to document the effects of a structured, multiday intervention—labelled the "Working with Addiction and Stress" retreats—that combined group counselling and two Shipibo-style ayahuasca ceremonies. Thomas and colleagues aimed to assess whether participation would be associated with improvements in emotional regulation, mindfulness, empowerment, hopefulness and quality of life, and with reductions in problematic substance use. The investigators also collected semi-structured qualitative interviews six months after the retreats to capture participants' subjective experiences and to supplement the psychometric and behavioural measures.

Ethics approval was obtained from an independent Institutional Review Board Services, and the study took place after consultation and consent with the band Council and Elders. Recruitment was undertaken by the band's health office: 18 community members volunteered across two retreats (June and September 2011). Inclusion criteria were voluntary attendance and English communication; safety-related exclusions applied to persons under 18, anyone who had previously drunk ayahuasca, those taking selective serotonin reuptake inhibitors or monoamine oxidase inhibitors, and people currently experiencing psychosis or with a recent psychotic break. Participants attended a group orientation, provided written consent, and completed baseline self-administered surveys. The intervention comprised a four-day, three-night retreat held in the band's longhouse. Each retreat included two ayahuasca ceremonies (one on the second night and one on the third), led by a Shipibo master ayahuasquero and apprentice ayahuasqueros, and multiple group therapy sessions focused on reflection about addictions, psychosomatic exercises and peer sharing. Traditional dietary restrictions and ceremonial practices (e.g., steam/sweat lodge, icaros, sopladas) were observed. The brew was prepared according to Shipibo customs and doses were determined by the ayahuasqueros; no chemical analysis of the brew was performed. Quantitative outcomes were measured with validated psychometric instruments administered at baseline, immediately post-retreat (State of Consciousness Questionnaire, SOCQ, administered but not analysed here), and at multiple follow-ups up to six months. Instruments included the Difficulty in Emotion Regulation Scale (DERS), Philadelphia Mindfulness Scale (PHLMS), Empowerment Scale (ES), Hope Scale (HS), McGill Quality of Life (MQL) with subscales (physical, psychological, outlook, meaning), and a 4 Week Substance Use Scale (4WSUS) adapted from WHO ASSIST. A semi-structured interview was added (after amended ethics approval) for the seventh follow-up to capture qualitative reflections on impact, connection and differences from prior treatments. For statistical analysis, scale scores were computed and missing item responses were mean-imputed when fewer than 20% of items per scale were missing (this affected under 5% of items overall). Because participants were measured repeatedly, the investigators used one-group repeated-measures ANOVA on each scale; follow-up timepoints were aggregated (means of 2nd+3rd, 4th+5th, 6th+7th) to yield five temporal data points. Sphericity was tested with Mauchly's W and corrections applied if violated; trend analyses were conducted for significant measures. A secondary repeated-measures ANOVA tested interactions for the subset (n=4) who attended two retreats. Semi-structured interviews were transcribed; two questions were quantified and answers to an open question underwent content analysis.

Of 18 people recruited, 12 participants had complete data after imputation and aggregation and were included in the primary analyses. Two volunteers did not attend, one left early for medical reasons, and three had insufficient follow-up data. No serious adverse psychological or physical events were reported to the research team or the band's health office during the six-month follow-up period. Psychosocial measures showed several statistically significant improvements over time (p < .05). Mindfulness (PHLMS), empowerment (ES), hopefulness (HS), and two McGill Quality of Life subscales—meaning and outlook—improved significantly. Emotional regulation (DERS), overall quality of life and the psychological subscale improved numerically but did not reach statistical significance. Trend analyses indicated a sustained linear increase for mindfulness and hope, while the quality-of-life meaning subscale exhibited a quadratic pattern (initial rise, dip, then consistent increase after the third data point). Internal consistency at baseline varied across scales (Cronbach's alpha range 0.408–0.929); both hope and mindfulness had alphas below 0.700, which the authors note as a limitation for psychometric reliability. Substance-use findings were mixed. The proportion of participants reporting past-month alcohol, tobacco and cocaine use was lower at the six-month follow-up than at baseline, whereas cannabis and opiate use showed no change; one participant reported hallucinogen use late in the study. Four-week Substance Use Scale (4WSUS) scores fell for tobacco, alcohol and cocaine but not for cannabis. A statistically significant linear reduction over time was documented for problematic cocaine use (reported p = 0.003 for the cocaine ASSIST scores' linear component). The investigators note that some participants were using prescribed medications (including methadone or medical cannabis), which may account for unchanged use of some substances. Qualitative data came from semi-structured interviews with eleven participants at six months. All eleven reported that the retreat affected their lives; the mean rating on a 1–10 impact scale was 7.95 (eight participants rated it 8 or higher, none rated below 5). Interview themes included strengthened connection with self, improved family and social relationships, enhanced connection with nature or spirit, and reduced cravings or cessation of problematic use; participants contrasted the retreats with prior treatments, describing the experience as deeper or more spiritually meaningful. Representative participant quotations were provided in the paper to illustrate these themes. The SOCQ data were collected but not analysed in this report.

The investigators interpret their findings as showing that participation in the "Working with Addiction and Stress" retreats correlated with improvements in several psychosocial domains—mindfulness, empowerment, hopefulness—and with better quality of life in terms of meaning and outlook. They also report an association with reductions in problematic substance use, most notably cocaine. Thomas and colleagues suggest these changes could plausibly contribute to recovery by enhancing participants' ability to make conscious, health-promoting choices rather than acting on compulsive urges. In placing their results in context, the authors note consistency with prior observational reports from ayahuasca-using religious communities and with broader literature on psychedelics as potential catalysts for personal transformation and addiction recovery. They hypothesise possible psychological mechanisms (for example, increased openness or spiritually meaningful experiences) but acknowledge that this study was not designed to disentangle the relative contributions of pharmacology, the group counselling, ceremonial or ancillary practices (sweat lodges, spirit baths), or intercultural dynamics between Shipibo facilitators and First Nations participants. The paper emphasises several important limitations. The small convenience sample and lack of matched controls prevent causal inference and limit generalisability. Substance-use outcomes were based on self-report without biological verification. There was no chemical analysis of the ayahuasca brew and dosing varied according to traditional criteria, so dose–response relationships could not be explored. Some participants received concurrent prescribed treatments (e.g. methadone, medical cannabis), and four individuals attended two retreats, complicating interpretation. The authors also acknowledge that intercultural ceremonial exchange itself might have independent salutogenic effects. Given these uncertainties, they recommend larger, more rigorous studies—including randomised controlled trials and research focused on people who have not responded to conventional treatments—to determine safety, efficacy, and which components of the intervention are therapeutic.

The study concludes that this form of ayahuasca-assisted group therapy was correlated with statistically significant improvements in mindfulness, empowerment, hopefulness and quality of life (outlook and meaning), and may have contributed to a statistically significant reduction in problematic cocaine use. These preliminary findings align with prior observational reports of salutogenic effects from ceremonial ayahuasca drinking, but the authors emphasise the need for further research—particularly controlled clinical trials—to determine whether ayahuasca-assisted interventions can be a safe and effective adjunct for treating addictions in populations that have had poor outcomes with conventional approaches.