This follow-up study (n=36) found that the mystical experience on the day of the psychedelic experience (58% had a ‘full’ experience) with psilocybin (30mg/70kg) mediated the level of personal meaning and spiritual significance reported 14 months later.
“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.”
This study builds on the earlier work done by Griffiths et al (2006).
“The measures of personality, affect, quality of life, and spirituality assessed at screening indicated that the volunteers were generally well-adjusted, outgoing, open and high in spirituality.”
One should always stay cognisant of a (self) selection of the participants. In this case the high score on spirituality also manifested itself at the screening at a score of about 210 (college students on average scored 195) and 250 after 2 and 14 months after the psilocybin session(s).
The paper also does a good job of describing the mystical experience from the point of view of the participants. In table 3 you can find their quotes. E.g.
“The experience expanded my conscious awareness permanently. It allows me to let go of negative ideas faster. I accept ‘what is’ easier.”