Psilocybin-occasioned mystical-type experience in combination with meditation and other spiritual practices produces enduring positive changes in psychological functioning and in trait measures of prosocial attitudes and behaviors

Quantum change experiences are described as sudden, deeply meaningful events that can produce broad, lasting changes in emotions, cognition and behaviour. Earlier experimental work has shown that under supportive conditions psilocybin reliably occasions mystical-type experiences that participants often attribute to enduring improvements in well-being, but prior controlled studies in healthy volunteers have provided limited evidence for persistent changes on well-validated trait measures. The authors note that older clinical reports and recent therapeutic trials (for example in cancer-related distress) suggest potential for longer-term benefits, but systematic, prospective investigation of enduring trait-level changes in healthy people has been sparse. This study sought to test whether psilocybin dose and the intensity of support for a structured programme of meditation and other spiritual practices produce enduring positive changes in prosocial attitudes, behaviours, and psychological functioning. Griffiths and colleagues randomised healthy participants into three groups (very low-dose with standard support; high-dose with standard support; high-dose with high support), administered two double-blind psilocybin sessions about one month apart after initiation of spiritual practices, and assessed acute effects, participant attributions, engagement with spiritual practice, and a battery of longitudinal trait measures up to 6 months after baseline. The design therefore aimed to examine both pharmacological and contextual (practice/support) determinants of lasting change.

This was a randomised, double-blind experimental study in healthy volunteers that manipulated psilocybin dose (very low active placebo vs high dose) and the intensity of support for spiritual practice (standard vs high). Of 1305 telephone screens and 184 in-person screens, 85 volunteers were enrolled and 75 completed the study; randomisation yielded three groups of 25 each: LD-SS (1 mg/70 kg on both sessions, standard support), HD-SS (20 mg then 30 mg/70 kg, standard support), and HD-HS (20 mg then 30 mg/70 kg, high support). Two psilocybin sessions were separated by about 1 month and were administered in a living-room-like setting with two guides present; a subset later received a third session after the 6-month assessment to obscure expectancy, but third-session data are not reported here. Urn randomisation balanced groups on six dichotomous variables (gender, age, lifetime psychedelic use, baseline lifetime Hood Mysticism score, baseline meditation frequency, and staff judgement of likelihood to engage in spiritual practices). Participants were medically and psychiatrically screened, excluded for psychotic or bipolar disorder history and recent substance dependence; 25% reported remote prior psychedelic use (mean ~25 years since last use) and individuals with prior salient mystical-type experiences were excluded. Guides provided preparatory meetings and session support; the standard-support condition involved about 7 hours 20 minutes of guide contact across the study, whereas the high-support condition provided about 35 hours including twice-monthly 90-minute dialogue groups focused on implementing meditation, daily awareness practice and journaling. All participants received the same nonsectarian teaching materials and were instructed in three core practices: daily sitting meditation (10–30 minutes), daily awareness practice, and daily self-reflective journaling. Physiological and observational measures were collected repeatedly during sessions (blood pressure, heart rate, guide Monitor Rating Questionnaire). At about 7 hours post-capsule participants completed subjective measures including the Hallucinogen Rating Scale (HRS), 5-Dimensional Altered States of Consciousness (5D-ASC), Mysticism Scale and the States of Consciousness Questionnaire from which the Mystical Experience Questionnaire (MEQ30) was derived; a “complete” mystical experience required ≥60% of the maximum on each of four MEQ30 factors. Longer-term assessments at baseline and 6 months comprised a broad battery of validated trait measures (e.g. Hood Mysticism Scale, Faith Maturity Scale, Daily Spiritual Experience Scale, Death Transcendence Scale, Gratitude Questionnaire, Purpose in Life, Nonattachment Scale, NEO personality inventory etc.), a persisting effects questionnaire at 6 months (140 items across attitudes, mood, relationships, behaviour, spirituality), a spiritual practices questionnaire (retrospective past-4-month frequency/duration), and community observer ratings conducted by telephone. An open-ended clinical interview at 6 months queried persisting adverse events. Statistical analyses used ANOVA for session and single time-point comparisons (SAS PROC GLM), repeated measures regression with AR(1) covariance (SAS PROC MIXED) for baseline-to-6-month longitudinal analyses, and planned comparisons between groups. Time-course session data used peak scores and time-to-peak analyses. Hierarchical regression examined contributions of the three spiritual practice measures (entered together) and MEQ30 mean total score (entered second, and in alternate analyses entered first) to variance in outcome measures. Blinding integrity was assessed post-study by querying primary guides about perceived drug/dose conditions.

Sample and blinding. Seventy-five participants completed the study (25 per group), mean age 42, 40% male, 89% with college or postgraduate degrees. Most were psychedelic-naive and participants with prior salient mystical experiences were excluded. Post-study queries indicated that guides generally did not correctly infer study dose conditions, suggesting partial success of blinding, though some guides made varied incorrect inferences about drugs and dose levels. Acute session effects. Compared with the very low-dose group, both high-dose groups showed larger acute physiological and observer-rated effects. Peak cardiovascular effects (systolic and diastolic blood pressure, heart rate) and most guide Monitor Rating dimensions were significantly greater in HD-SS and HD-HS than LD-SS; peak cardiovascular impact occurred broadly within 30–180 minutes and guide ratings peaked later (around 180 minutes). Differences between the two high-dose sessions (20 mg then 30 mg) were minimal for subjective and guide-rated measures, though peak heart rate occurred earlier at the higher dose and peak systolic/diastolic pressures were modestly higher after 30 mg. Mystical-type experiences. End-of-day subjective measures (HRS, 5D-ASC, Mysticism Scale, MEQ30) paralleled session ratings: both high-dose groups were consistently higher than LD-SS. Proportions meeting criteria for a "complete" MEQ30 mystical experience were markedly different by group: session 1/2 rates were 0%/4% (LD-SS), 48%/50% (HD-SS), and 44%/52% (HD-HS). Across either or both sessions, 4% of LD-SS, 61% of HD-SS, and 64% of HD-HS participants met criteria for a complete mystical experience. Engagement with spiritual practices at 6 months. Participants in the high-support condition practised substantially more: averaged over the last 4 months, HD-HS reported ~19.3 minutes meditation per day, 5.2 spiritual-awareness practices per day, and 4.4 journaling sessions per week—approximately double rates in the standard-support groups. The HD-HS group was significantly higher than LD-SS and HD-SS on multiple engagement measures; LD-SS and HD-SS did not differ significantly, indicating dose alone did not increase practice frequency under these conditions. Persisting effects at 6 months (participant attributions). On the persisting effects questionnaire, both high-dose groups reported substantially greater positive enduring changes attributed to the psilocybin sessions across attitudes, mood, altruism/social effects, behaviour, and spirituality. Effect sizes for these comparisons were large (mean Cohen's d=1.65). The HD-HS group exceeded HD-SS on altruistic/positive social effects, positive behaviour changes, and increased spirituality. Ratings of personal meaning and spiritual significance were higher in both high-dose groups versus LD-SS; for example, being among the top five most spiritual experiences was rated by 12% (LD-SS), 76% (HD-SS), and 96% (HD-HS), and being the single most spiritually significant experience by 0%, 40%, and 56%, respectively. Longitudinal trait measures and observer ratings. Of the longitudinal battery, 23 measures demonstrated significant between-group differences at 6 months. Comparing LD-SS with HD-SS, 14 of these 23 measures showed significant differences in the expected (positive) direction. The HD-HS group differed significantly from LD-SS on all 23 measures and from HD-SS on 14 of 23 measures. Within-group baseline-to-6-month changes were significant on 20 of 23 measures in HD-HS, 17 of 23 in HD-SS, and only 1 of 23 in LD-SS. These measures included interpersonal closeness, gratitude, life meaning/purpose, forgiveness, death transcendence, daily spiritual experiences, faith and coping, sanctification of strivings and community observer ratings. Mean effect size across the 23 measures was large (mean Cohen's d≈1.0). Openness (NEO) increased from baseline to 6 months only in HD-HS, but there was no significant between-group difference at 6 months on Openness or other NEO domains. Determinants of enduring change. Hierarchical regression showed that the three spiritual practice measures together accounted for significant variance in 13 of 19 examined outcomes (R2 range .050–.293, mean .139). Adding MEQ30 score in the second step accounted for a significant incremental proportion of variance in 18 of 19 measures (ΔR2 range .031–.619, mean .266). When MEQ30 was entered first it accounted for significant variance in all 19 measures (R2 range .123–.747, mean .351). Overall, mystical experience scores explained more variance than do the practice measures, though both contributed to outcomes. Safety and adverse events. No serious adverse events attributable to psilocybin or study procedures occurred. Transient moderate increases in blood pressure were common; one participant required sublingual nitroglycerin for diastolic hypertension and was subsequently discontinued. No clinically significant persisting perceptual disturbances or non-study psychedelic use were reported at 6 months, and participants remained psychiatrically well in open-ended interviews.

Griffiths and colleagues interpret the findings as evidence that psilocybin, administered in a supportive environment that encourages a nonsectarian programme of meditation and spiritual practices, can occasion mystical-type experiences that are meaningfully associated with enduring positive changes in prosocial attitudes, behaviours and psychological functioning. The double-blind dose manipulation and use of a very low active control aimed to reduce expectancy confounds, and the results show robust acute and persisting differences between high- and very low-dose conditions on multiple subjective, behavioural and observer-rated outcomes. The study team emphasises that the present results differ from earlier healthy-volunteer studies that largely failed to find sustained trait changes; they attribute this difference plausibly to the additional contextual support for spiritual practice and integration provided in the present protocol. Evidence that HD-HS exceeded HD-SS on many session-day mystical measures, sustained practice rates, persisting attributions, and longitudinal trait outcomes supports an interaction between pharmacological effects (psilocybin-occasioned mystical experience) and engagement in spiritual practice. Hierarchical regressions indicate that while spiritual practices themselves explain some variance in outcomes, the intensity of the psilocybin-occasioned mystical experience (MEQ30) accounts for a larger proportion of variance across outcome measures, and MEQ30 scores temporally preceded the 6-month assessments. The authors acknowledge several limitations. The low-dose condition may not have been a true inert placebo, leaving open the possibility of pharmacological activity at 1 mg/70 kg; blinding was assessed only post hoc for guides and not systematically after each session; the study did not include a low-dose high-support cell which would have isolated support effects independent of dose; the sample was demographically homogeneous (predominantly White, highly educated, employed), limiting generalisability; and no brain-based or task-based physiological measures were collected. In addition, because the high-support condition combined enhanced individual guidance with group dialogue about both spiritual practice and psilocybin experiences, the unique contribution of group discussion versus practice support cannot be disentangled. The authors therefore call for replication, mechanistic studies (including direct comparisons with other psychedelics), and investigation in more diverse samples and clinical populations. Overall, the investigators conclude that psilocybin-occasioned mystical experience together with regular engagement in meditation and related practices appears to be a determinant of sustained increases in prosocial attitudes, positive psychological functioning and life meaning, when administered under the tested spiritually supportive conditions.

The authors conclude that when psilocybin is administered within a framework that fosters ongoing meditation and spiritual practices, high doses can produce enduring, trait-level increases in prosocial attitudes, behaviours and measures of psychological functioning at 6 months. Analyses indicate that the intensity of the psilocybin-occasioned mystical experience and the degree of engagement with spiritual practices were key determinants of these lasting effects. The study frames psilocybin-occasioned experiences as a model for experimentally investigating so-called quantum change experiences and suggests further research to explore therapeutic and non-therapeutic applications for engendering enduring positive changes in attitudes and behaviour.