Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance

The extracted Introduction is brief. It identifies psilocybin as a naturally occurring tryptamine alkaloid whose actions are mediated primarily at serotonin 5-HT2A/C receptor sites and states that it is the principal psychoactive component of a genus of psychedelic mushrooms. The text establishes the pharmacological basis for studying psilocybin but the extraction truncates further contextual detail about prior empirical work and the specific gaps the study addresses. Using the available extraction, the study's aim can be inferred from later sections: to evaluate, under controlled and supportive conditions, whether a high dose of psilocybin can occasion acute mystical-type experiences and whether such experiences have persisting personal meaning, spiritual significance, and effects on attitudes and behaviour compared with an active control (methylphenidate).

Griffiths and colleagues conducted a double-blind, crossover study comparing a high dose of psilocybin (30 mg/70 kg) with an active comparator, methylphenidate (40 mg/70 kg). The study involved two or three individually conducted 8-hour drug sessions at approximately 2-month intervals. Of 36 volunteers enrolled, 30 were randomly assigned to the main counterbalanced two-session condition (15 received psilocybin first, 15 methylphenidate first) and six received methylphenidate on the first two sessions with an unblinded psilocybin third session; data from those six were not included in the primary statistical analyses but were reported as generally consistent with main results. The participants were hallucinogen-naïve, medically and psychiatrically healthy adults (N=36; 14 males), averaging 46 years of age, well educated, and reporting regular participation in religious or spiritual activities. Preparation for sessions included multiple meetings with primary and assistant monitors (a clinical psychologist and a clinically trained social worker) to build rapport and review life history; these meetings aimed to reduce adverse reactions and set expectations that sessions could increase personal insight while avoiding explicit mention of the mystical-experience assessment criteria. Drug sessions were individual, conducted in a living-room-like environment, and encouraged inward attention: participants usually lay down, wore an eye mask, and listened to a standard classical music programme via headphones. Two monitors remained with each participant throughout. Physiological measures (blood pressure, heart rate) and monitor ratings were recorded repeatedly during sessions. Outcome assessments were made at multiple time points. About 7 h after administration (when acute effects had subsided) participants completed three drug-sensitive questionnaires (Hallucinogen Rating Scale, APZ, ARCI) and two mystical-experience instruments (States of Consciousness Questionnaire incorporating the Pahnke–Richards Mystical Experience Questionnaire items, and the Mysticism Scale). Longitudinal measures were administered at 7–8 weeks post-session and included a Persisting Effects Questionnaire (developed for the study to capture changes in attitudes, mood, social effects and behaviour, plus ratings of personal meaningfulness and spiritual significance), lifetime versions of mysticism/spirituality scales, NEO PI-R (personality), and PANAS-X (affect). Community observer ratings (designated friends/family) were obtained by structured telephone interview before the study and 7–8 weeks after each session to assess observable changes. Blinding integrity was assessed by monitor guesses; approximately 23% of sessions were misclassified by one or both monitors. Statistical analysis used within-subject two-factor ANOVA (drug × time) for timecourse data with Tukey HSD post hoc tests, paired t tests for most drug comparisons at single time points, and planned t-test comparisons for longer-term personality/spirituality measures to address potential carry-over effects.

Physiological and within-session observations: Both psilocybin and methylphenidate produced orderly, time-related increases in blood pressure and heart rate (heart rate rose by about 10 bpm for both drugs), with effects typically onset at 30–60 min, peaking between 90 and 180 min, and declining thereafter. Monitor ratings indicated substantially greater overall drug effect for psilocybin than for methylphenidate. Participants under psilocybin were rated as less responsive to questions, more removed from ordinary reality, and more emotionally labile, showing higher peak ratings of tearing/crying, anxiety/fearfulness, joy/intense happiness, and peace/harmony. Behaviourally, participants spent more minutes talking after methylphenidate than after psilocybin (72 vs 51 min in the 6 h after ingestion), whereas physical contact with monitors was greater after psilocybin (58 vs 24 min). Psilocybin produced higher peak stimulation/arousal and spontaneous motor activity in monitor ratings. Acute subjective drug- and mysticism-sensitive questionnaires (≈7 h post-dose): On hallucinogen-sensitive instruments, psilocybin scored higher than methylphenidate on all six Hallucinogen Rating Scale subscales, all three APZ scales (oceanic boundlessness, dread of ego dissolution, visionary restructuralization), and the LSD-sensitive scale of the ARCI. Other ARCI subscales showed mixed results: PCAG (sedative-sensitive) was higher after psilocybin, the A (amphetamine) scale was higher after psilocybin, BG (benzedrine group) was higher after methylphenidate, and MBG (euphoria) did not differ between drugs. On designated measures of mystical experience, psilocybin produced significantly higher scores: the Mysticism Scale total and its three factors, and all seven subscales of the States of Consciousness Questionnaire, were greater after psilocybin. Using a priori criteria (scale scores ≥0.6 on key domains), 22 of 36 volunteers (61%) met criteria for a "complete" mystical experience after psilocybin, whereas only 4 of 36 did so after methylphenidate. Persisting effects at 2 months: On the Persisting Effects Questionnaire (completed by 24 participants in the relevant sample), psilocybin produced significantly greater increases in ratings of positive attitudes about life/self, positive mood, altruistic/positive social effects, and positive behaviour change than methylphenidate; negative ratings were low and did not differ between conditions. Personal meaningfulness and spiritual significance ratings were markedly higher after psilocybin: 67% of volunteers rated the psilocybin session among the top five or the single most meaningful experience of their lives, 33% rated it the single most spiritually significant experience, and a further 38% rated it among the top five spiritually significant experiences. Regarding life satisfaction, 79% of volunteers rated that psilocybin increased their current sense of personal well-being or life satisfaction moderately (50%) or very much (29%), compared with 17% and 4% respectively after methylphenidate; no volunteer reported a decrease. Personality, affect, lifetime mysticism/spirituality, and observer ratings: Standard measures of personality (NEO PI-R) and average positive/negative affect (PANAS-X) showed no differential change attributable to drug condition. Lifetime measures of mysticism and spiritual transcendence increased in the groups after psilocybin exposure in the expected session-order pattern (scores rose in participants after their psilocybin session and, as lifetime measures, did not subsequently decrease). Community observers reported small but significant positive changes in participant attitudes and behaviour after psilocybin compared with methylphenidate. Adverse events and blinding integrity: During sessions, anticipatory anxiety was common; 11 of 36 volunteers reported their experience of fear as "strong" or "extreme" at some point after psilocybin (none after methylphenidate). Eight volunteers had notable episodes of anxiety/dysphoria, four of whom described sessions dominated by distress; six of these eight had transient ideas of reference/paranoid thinking during the 6-hour session. These acute effects were managed with reassurance and did not persist beyond the session; no pharmacological interventions were required. Blinding was reasonably preserved: monitors misclassified 23% of sessions overall (primary monitor 17% misclassification), and some methylphenidate sessions were mistaken for psilocybin and vice versa. At the (ongoing) 1-year follow-up completed by most participants, no persisting perceptual disturbances or recreational abuse attributable to the study had been reported.

Griffiths and colleagues interpret the results as evidence that, under comfortable, structured, and interpersonally supportive conditions, a high dose of psilocybin can occasion experiences that closely resemble classical descriptions of mystical experience and that these experiences are judged by participants to have substantial and sustained personal meaning and spiritual significance. The volunteers also attributed lasting positive changes in attitudes and behaviour to their psilocybin experience, and these self-reports were broadly consistent with ratings made by community observers. The authors situate their findings relative to prior experimental attempts to elicit mystical experiences, noting improvements over earlier work (for example, better blinding, individual rather than group sessions, more extensive preparation, and validated outcome measures). They suggest that the comparatively high incidence of "complete" mystical experiences in this study (61%) versus some earlier reports may relate to greater preparation time and the individualised setting with music and eye masks. Limitations acknowledged include the selected sample — hallucinogen-naïve, middle-aged, well educated, psychologically stable individuals who reported regular religious or spiritual practice — which may limit generalisability and could have increased the likelihood of interpreting experiences as spiritually significant. The authors also note that novelty effects in hallucinogen-naïve participants cannot be ruled out. Expectancy effects were addressed by study design features (active control, obscuring of design, monitor training), but cannot be entirely eliminated. In terms of safety and broader implications, the study indicates that with careful screening, preparation, and supervision a high dose of psilocybin can be administered without pharmacological rescue, though notable transient anxiety/dysphoria and brief paranoid ideation occurred in a subset of participants (22% experienced notable anxiety/dysphoria). The authors caution that these findings do not imply absence of risk outside controlled settings and that hallucinogens can produce harmful acute effects or potentially precipitate enduring psychiatric conditions in vulnerable individuals. Finally, they conclude that the capacity to prospectively occasion mystical-type experiences permits rigorous research into their causes and consequences, including pharmacological and neural mechanisms, and bears on questions about nonmedical use, abuse potential, and the short- and longer-term psychological effects of such experiences.