Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance, Roland R. Griffiths et al., 2006

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

Roland R. Griffiths, William A. Richards, Una McCann, Robert Jesse

Psychopharmacology, 2006

DOI 10.1007/s00213-006-0457-5



Rationale : Although psilocybin has been used for centuries for religious purposes, little is known scientifically about its acute and persisting effects.

Objectives : This double-blind study evaluated the acute and longer-term psychological effects of a high dose of psilocybin relative to a comparison compound administered under comfortable, supportive conditions.

Materials and methods : The participants were hallucinogennaïve adults reporting regular participation in religious or spiritual activities. Two or three sessions were conducted at 2-month intervals. Thirty volunteers received orally administered psilocybin (30 mg/70 kg) and methylphenidate hydrochloride (40 mg/70 kg) in counterbalanced order. To obscure the study design, six additional volunteers received methylphenidate in the first two sessions and unblinded psilocybin in a third session. The 8-h sessions were conducted individually. Volunteers were encouraged to close their eyes and direct their attention inward. Study monitors rated volunteers’ behavior during sessions. Volunteers completed questionnaires assessing drug effects and mystical experience immediately after and 2 months after sessions. Community observers rated changes in the volunteer’s attitudes and behavior.

Results : Psilocybin produced a range of acute perceptual changes, subjective experiences, and labile moods including anxiety. Psilocybin also increased measures of mystical experience. At 2 months, the volunteers rated the psilocybin experience as having substantial personal meaning and spiritual significance and attributed to the experience sustained positive changes in attitudes and behavior consistent with changes rated by community observers.

Conclusions : When administered under supportive conditions, psilocybin occasioned experiences similar to spontaneously occurring mystical experiences. The ability to occasion such experiences prospectively will allow rigorous scientific investigations of their causes and consequences.

Keywords : Psilocybin . Methylphenidate . Hallucinogen . Entheogen . Mystical experience . Spiritual . Religion . Anxiety . Humans



Psilocybin, a naturally occurring tryptamine alkaloid with actions mediated primarily at serotonin 5-HT2A/C receptor sites, is the principal psychoactive component of a genus of mushrooms (Psilocybe) (Presti and Nichols 2004). Psilocybin, in the form of these mushrooms, has been used for centuries, possibly millennia, within some cultures in structured manners for divinatory or religious purposes
(Wasson 1980; Stamets 1996; Metzner 2004). The psychological effects of psilocybin, which are similar to other classical serotonergically mediated hallucinogens [lysergic acid diethylamide (LSD), mescaline, and N,N-dimethyltryptamine (DMT)], include significant alterations in perceptual, cognitive, affective, volitional, and somatesthetic functions, including visual and auditory sensory changes, difficulty in thinking, mood fluctuations, and dissociative phenomena (Isbell 1959; Wolbach et al. 1962; Rosenberg et al. 1964).

Early clinical research with psilocybin in the 1950s and early 1960s attempted to study the effects of psilocybin without recognition of the powerful influences of set and setting (e.g., Isbell 1959; Hollister 1961; Malitz et al. 1960; Rinkel et al. 1960). Subsequent research, which included more preparation and interpersonal support during the period of drug action, found fewer adverse psychological effects, such as panic reactions and paranoid episodes, and increased reports of positively valued experiences (Leary et al. 1963; Metzner et al. 1965; Pahnke 1969). In response to the epidemic of hallucinogen abuse that occurred in the 1960s, clinical research with psilocybin and other hallucinogens largely ceased and has resumed only recently. Notably, Vollenweider and colleagues from Switzerland and Gouzoulis- Mayfrank from Germany have reported a series of studies that have characterized the acute subjective, physiological, and perceptual effects of psilocybin (e.g., Vollenweider et al. 1998; Gouzoulis-Mayfrank et al. 1999; Hasler et al. 2004; Carter et al. 2005).

In the present study, we sought to use rigorous doubleblind clinical pharmacology methods to evaluate both the acute (7 h) and longer-term (2 months) mood-altering and psychological effects of psilocybin (30 mg/70 kg) relative to an active comparison compound (40 mg/70 kg methylphenidate). The study was conducted with 36 well-educated, hallucinogen-naïve volunteers.