Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later, Roland R. Griffiths et al., 2008

Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later

Roland R. Griffiths ,W.A. Richards , Matthew W. Johnson, Una D. McCann, R. Jesse

Journal of Psychopharmacology, 2008, 1–12.

Doi : 10.1177/0269881108094300



Psilocybin has been used for centuries for religious purposes; however, little is known scientifically about its long-term effects. We previously reported the effects of a double-blind study evaluating the psychological effects of a high psilocybin dose. This report presents the 14-month follow-up and examines the relationship of the follow-up results to data obtained at screening and on drug session days. Participants were 36 hallucinogen-naïve adults reporting regular participation in religious/ spiritual activities. Oral psilocybin (30 mg/70 kg) was administered on one of two or three sessions, with methylphenidate (40 mg/70 kg) administered on the other session(s). During sessions, volunteers were encouraged to close their eyes and direct their attention inward. At the 14-month follow-up, 58% and 67%, respectively, of volunteers rated the psilocybin-occasioned experience as being among the five most personally meaningful and among the five most spiritually significant experiences of their lives; 64% indicated that the experience increased well-being or life satisfaction; 58% met criteria for having had a ‘complete’ mystical experience. Correlation and regression analyses indicated a central role of the mystical experience assessed on the session day in the high ratings of personal meaning and spiritual significance at follow-up. Of the measures of personality, affect, quality of life and spirituality assessed across the study, only a scale measuring mystical experience showed a difference from screening. When administered under supportive conditions, psilocybin occasioned experiences similar to spontaneously occurring mystical experiences that, at 14-month follow-up, were considered by volunteers to be among the most personally meaningful and spiritually significant of their lives.

Keywords : entheogen; hallucinogen; humans; mystical experience; psilocybin; psychedelic; religion; spiritual



Although many have anecdotally claimed that psilocybin, the principal psychoactive component of various hallucinogenic mushroom species, can facilitate experiences providing sustained, positively valued impact, little is known scientifically about such effects. Psilocybin has been used as a sacrament for centuries, possibly millennia, in structured religious ceremonies (Wasson, 1980; Stamets, 1996; Metzner, 2004). Like other classical hallucinogens [d-lysergic acid diethylamide (LSD), mescaline, N,N-dimethyltyrptamine (DMT)], the effects of psilocybin are primarily mediated at 5-HT2A receptor sites (Nichols, 2004), and the acute subjective effects include robust changes in perception, cognition, affect, volition and somaesthesia (Isbell, 1959; Wolbach, et al., 1962; Rosenberg, et al., 1964).

The degree to which responses to psilocybin are influenced by nonpharmacological variables was not understood by early researchers (e.g. Isbell, 1959; Malitz, et al., 1960; Rinkel, et al., 1960; Hollister, 1961). By providing more preparation and interpersonal support during drug action, subsequent research described more positively valued experiences and fewer adverse effects (e.g. panic and paranoia) (Chwelos, et al., 1959; Leary, et al., 1963; Metzner, et al., 1965; Pahnke, 1969). In response to
the hallucinogen abuse of the 1960s, human hallucinogen research largely ceased and has only recently resumed. Notably, Vollenweider and colleagues in Switzerland and Gouzoulis-Mayfrank and colleagues in Germany have studied the neurocognitive, perceptual and psychosis-mimicking effects of psilocybin (e.g. Vollenweider, et al., 1998; Gouzoulis- Mayfrank, et al., 1999; Hasler, et al., 2004; Carter, et al., 2005, 2007).

Recently, we used rigorous double-blind methods to evaluate the acute (7 h) and longer term (2 months) psychological effects of a high dose of psilocybin (30 mg/70 kg) relative to an active comparison compound (40 mg/70 kg methylphenidate) in 36 hallucinogen-naïve volunteers (Griffiths, et al., 2006). In contrast to the aforementioned recent psilocybin studies, the study optimized the potential for positively valued experiences by providing 8 h of preparation and by instructing volunteers to focus explicitly on the phenomenology of the drug experience rather than perform tasks. The results showed psilocybin to occasion experiences with substantial personal meaning and spiritual significance when evaluated 2 months after psilocybin. We have subsequently conducted a follow-up study evaluating effects at 14 months after their last drug session. Volunteers completed questionnaires that assessed personality, affect, quality of life, spiritual experience, and persisting changes in attitude and behaviour attributed to the blinded psilocybin session. This report analyses these 14-month follow-up results and the contribution of baseline characteristics and immediate drug effects to long-term persisting effects.