The Shipibo Ceremonial Use of Ayahuasca to Promote Well-Being: An Observational Study

Gonzalez and colleagues frame this study within growing international interest in promoting well-being as a core public‑health and clinical objective. They contrast two traditions in well‑being research—the eudaimonic model (focusing on personal growth, autonomy, purpose and related constructs) and the hedonic model (focusing on life satisfaction and positive affect)—and note that both are relevant for comprehensive measurement. The authors situate ayahuasca within the wider category of traditional medicine, review its botanical composition (Banisteriopsis caapi and Psychotria viridis), prior evidence of safety from long‑term ceremonial use and laboratory studies, and emerging clinical findings that ayahuasca can have rapid antidepressant effects. They also note the global spread of ayahuasca practices and attendant concerns about cultural appropriation, variable practitioner competence, and lack of regulation. This prospective observational study set out to evaluate whether participation in a series of Shipibo‑led ayahuasca ceremonies at the Temple of the Way of Light (Iquitos, Peru) is associated with changes in multiple dimensions of well‑being over one year. The primary outcome was psychological well‑being; secondary outcomes included subjective happiness, spiritual well‑being, quality of life, and decentering. The investigators additionally planned to explore whether changes in decentering were associated with, and potentially mediated, changes in psychological well‑being. The study is presented as complementary to randomised trials, aiming to examine outcomes in a naturalistic, traditional healing context.

The study used a prospective, longitudinal, observational design. Participants were Western adults who had booked a retreat (9, 12, or 30 days) at the Temple of the Way of Light between 2015 and 2017 and provided online informed consent; ethical approval was granted by the Autonomous University of Barcelona ethics committee. Screening followed the centre's usual criteria: participants had to be 18 or older and were excluded if they had certain psychiatric diagnoses (psychosis, mania, depersonalisation), were taking contraindicated medications (e.g. MAOIs, SSRIs), had cardiovascular conditions, chronic high blood pressure, or were pregnant. Additional inclusion for this analysis required absence of current depression, anxiety, posttraumatic stress or grief and adequate English comprehension. Assessments were administered online at multiple timepoints: an optional T-1 (two months before the retreat) for a subgroup; baseline T0 (15 days before the retreat); T1 (15 days after leaving the centre); and follow‑ups at 3 months (T2), 6 months (T3), and 12 months (T4). Only participants who completed both T0 and T1 were included in the primary analytic sample. Data were collected with LimeSurvey and stored securely. Several validated self‑report instruments were employed. Psychological Well‑Being was measured with the 42‑item PWBS (six subscales); subjective well‑being with the 29‑item Oxford Happiness Questionnaire; spiritual well‑being with the WHOQOL‑SRPB; quality of life with the WHOQOL‑BREF (physical, psychological, social domains were used); and decentering with the 11‑item EQ‑Decentering scale. Two ayahuasca brew samples collected during enrolment were analysed by LC‑MS to quantify DMT and ß‑carbolines; concentrations for the two samples are reported in the text. Statistical analysis was performed in SPSS. Descriptive statistics were used for baseline and setting variables. Changes from baseline to each follow‑up were tested with paired t‑tests or Wilcoxon tests as appropriate, with Bonferroni correction for multiple comparisons. Effect sizes were calculated as Cohen's d, and 95% confidence intervals for means were reported for the primary outcome. Pearson correlation coefficients examined the association between change in decentering and change in psychological well‑being. A pre‑planned subgroup analysis (n=42) that included T-1, T0 and T1 used repeated measures ANOVA to help distinguish effects of the retreat from routine temporal change.

Of 437 people assessed for eligibility, 200 participants completed both baseline (T0) and post‑retreat (T1) assessments and constituted the primary analytic sample. Attrition at subsequent follow‑ups was substantial: non‑response rates were 49.5% at T2, 54.5% at T3, and 53% at T4. The sample reported motivations of spiritual growth (66.7%) and personal development (32.4%); 65.5% were ayahuasca‑naïve prior to the retreat. Participants spent on average 14.93 days (SD 7.58, range 9–31) at the centre and took part in a mean of 6.21 ceremonies (SD 1.57, range 1–12). When asked about the most relevant factor in their well‑being change during the stay, 54% cited ayahuasca, 36% the Shipibo healers, with smaller proportions citing other factors. Primary outcome: Psychological Well‑Being Scale total scores increased significantly from baseline at all post‑retreat timepoints (T1–T4, p < 0.01). Effect sizes were large across assessments: T1 d = 0.89 (95% CI 0.72–1.04), T2 d = 0.91 (95% CI 0.67–1.11), T3 d = 1.12 (95% CI 0.89–1.35), and T4 d = 0.82 (95% CI 0.56–1.07). Self‑acceptance was the PWBS subscale showing the largest improvement. Secondary outcomes: Subjective well‑being (Oxford Happiness) improved significantly at all follow‑ups (p < 0.01) with effect sizes ranging from moderate to large (T1 d = 0.76, 95% CI 0.62–0.90; T3 d = 0.91, 95% CI 0.68–1.12). The WHOQOL‑SRPB total score also showed significant increases at all timepoints (p < 0.01), with large effect sizes at several assessments (T1 d = 0.96; T3 d = 1.05; T4 d = 0.90). WHOQOL‑BREF domains (physical health, psychological health, social relationships) improved after the retreat, with the psychological health domain showing the largest effects (T1 d = 0.96, 95% CI 0.81–1.10; T3 d = 0.94, 95% CI 0.75–1.13). Decentering increased significantly at T1 and remained elevated at T2–T4 (all p < 0.01), exhibiting large effect sizes (T1 d = 0.97, 95% CI 0.82–1.12; T4 d = 0.87, 95% CI 0.61–1.10). Correlation and subgroup analyses: Change in decentering from T0 to T1 correlated moderately with change in PWBS total score over the same interval (r = 0.53; p < 0.01). In the subgroup (n = 42) who completed T-1, T0 and T1, repeated measures ANOVA showed no significant changes between T-1 and T0 but significant improvements between T0 and T1 across multiple measures, supporting the view that changes were associated with the retreat rather than the mere passage of time. Selected ANOVA results include Oxford Happiness F(2,82) = 26.14, p < 0.001 (T1 vs T0 effect size 0.99); WHOQOL‑SRPB F(1.4,57.3) = 49.02, p < 0.001 (d = 1.29); Psychological Health F(1.7,71.3) = 18.30, p < 0.001 (d = 0.83); Social Relationships F(2,80) = 22.00, p < 0.001 (d = 0.79); Decentering F(1.4,56.6) = 29.90, p < 0.001 (d = 0.95). Ayahuasca composition and use: LC‑MS of two brew samples found DMT at 2 mg/ml in both samples, harmine ∼2 mg/ml in both, harmaline 0.37–0.65 mg/ml, and tetrahydroharmine 1–2 mg/ml; no other psychoactive compounds were detected. At 3‑month follow‑up (T2) 92.5% expressed willingness to continue ayahuasca use, but 64.9% had not used ayahuasca in the 12 months after leaving the centre. Participants expressed concerns about risks when using ayahuasca in their home countries (92% reported exposure to various risks), including legal issues (71.3%), uncertainty about brew composition (40.8%), inability to consult professionals for adverse effects (26%), and personal safety/ethical practice concerns (40.3%). The authors report persistent benefits and adverse effects in a table, but detailed adverse‑event data are not fully presented in the extracted text.

Gonzalez and colleagues interpret their findings as evidence that participation in a series of Shipibo‑led ayahuasca ceremonies in a retreat context was associated with sustained increases in psychological, subjective, spiritual well‑being and quality of life up to one year. They highlight that the subgroup analysis including a T-1 assessment supports the view that these changes are attributable to the retreat period rather than to simple temporal trends. The authors emphasise decentering as an important psychological mechanism: decentering increased with a large effect size and its change correlated moderately with improvements in psychological well‑being, consistent with prior studies suggesting decentering as a mediator of psychedelic‑related benefits. The discussion positions these results alongside observational research and ritual use literature that reports elevated well‑being in long‑term ayahuasca users, and contrasts ceremonial ayahuasca practice with non‑ritual psychedelic use. The authors note the potential contribution of ritual, healer practice and contextual factors—what some frameworks call performative efficacy or contextual healing—in driving outcomes; 36% of participants judged the Shipibo healers’ work to be the most relevant factor in their well‑being change. They also advance a hypothesis that the benefits may reflect an experiential learning process triggered by intense, contextually rich experiences that can generate lasting changes in self‑regulation and meaning‑making. Several limitations are acknowledged. The naturalistic, non‑controlled design prevents isolation of ayahuasca's pharmacological effects from other components of the intervention (ceremony, healer work, group and environmental factors). Absence of a placebo or active control group precludes causal attribution. The sample is self‑selected, financially able to attend a retreat, and motivated by spiritual or personal growth, limiting generalisability. Recruitment was voluntary and not all retreatants were enrolled, and outcomes rely on self‑report measures subject to social desirability bias. The authors also raise ethical and policy considerations around vegetalismo's international uptake and the need for regulation to reduce risks for both Indigenous communities and international participants. Finally, they call for further research into vegetalismo as a traditional medicine system and for studies that explore mechanisms, safety and appropriate regulation, while noting that their data may support recognition of ayahuasca as an herbal medicine used within traditional contexts.