Symmetrical Global Mental Health (Sym-GMH): Ayahuasca and Shipibo Traditional Medicine for Lasting Changes in Personality and Quality of Life
About the study
A prospective, longitudinal study led by ICEERS researchers evaluated the psychological effects of ayahuasca retreats conducted by Shipibo healers at the Temple of the Way of Light in the Peruvian Amazon. Over twelve months, 264 Western participants completed assessments of personality, quality of life, decentering capacity, and psychiatric symptoms. Findings indicate significant changes across several personality dimensions, broad improvements in quality of life, and a notable increase in decentering capacities, with moderate to high effect sizes.
Some 91.7% of participants reported long-term benefits, primarily in spiritual wellbeing, mental health, and personal growth. Adverse effects were minimal, observed in only 2.3% of cases. The study also found that higher baseline psychological distress was associated with lower decentering capacity, suggesting that strengthening this ability may serve as a resilience factor against emotional suffering.
The study is framed within the Symmetrical Global Mental Health (Sym-GMH) paradigm, which proposes a reciprocal, non-extractive integration between traditional and Western medical systems. The findings suggest that Amazonian traditional medicine practices, when preserved in their cultural context and applied in an ethically responsible manner, can offer meaningful contributions to the mental health of Western populations — and open the door to genuine dialogue between healing paradigms.
Abstract
The Symmetrical Global Mental Health (Sym-GMH) paradigm proposes a reciprocal integration between traditional and Western medical systems. This prospective, longitudinal study evaluates the psychological outcomes of 264 Western participants who engaged in Shipibo-led ayahuasca retreats at the Temple of the Way of Light in the Peruvian Amazon. Over a 12-month period, participants completed assessments of personality (NEO-FFI), quality of life (WHOQOL-BREF), decentering (EQ-Decentering), and psychiatric symptoms (SA-45). The results showed significant reductions in Neuroticism and Openness to Experience and increase in Extraversion, with no significant change in Agreeableness and Conscientiousness. Quality of life improved across all measured domains, and decentering capacities increased significantly with moderate to high effects size. Most participants (91.7%) reported long-term benefits, primarily in spiritual well-being, mental health, and personal growth. Adverse effects were minimal (2.3%). Despite higher frequency of last month substances use was observed, increase on the prevalence was only observed for tobacco. Extraversion at baseline predicted improvements across all quality-of-life domains. Notably, higher baseline psychological distress was associated with higher Neuroticism and lower decentering, suggesting that enhancing decentering may serve as a resilience factor. These findings suggest that Amazonian traditional practices, when contextually preserved and ethically applied, can offer meaningful contributions to mental health in Western populations. The study supports the integration of traditional systems within global mental health frameworks, advocating for a non-extractive, culturally respectful, and evidence-based exchange between healing paradigms.