Original Investigation

Psychopharmacology

, Volume 218, Issue 4, pp 649-665

Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects

  • Roland R. GriffithsAffiliated withDepartment of Psychiatry and Behavioral Sciences, Johns Hopkins University School of MedicineDepartment of Neuroscience, Johns Hopkins University School of Medicine Email author 
  • , Matthew W. JohnsonAffiliated withDepartment of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine
  • , William A. RichardsAffiliated withDepartment of Psychiatry, Johns Hopkins Bayview Medical Center
  • , Brian D. RichardsAffiliated withDepartment of Psychiatry, Johns Hopkins Bayview Medical Center
  • , Una McCannAffiliated withDepartment of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine
  • , Robert JesseAffiliated withCouncil on Spiritual Practices

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Abstract

Rationale

This dose-effect study extends previous observations showing that psilocybin can occasion mystical-type experiences having persisting positive effects on attitudes, mood, and behavior.

Objectives

This double-blind study evaluated psilocybin (0, 5, 10, 20, 30 mg/70 kg, p.o.) administered under supportive conditions.

Methods

Participants were 18 adults (17 hallucinogen-naïve). Five 8-h sessions were conducted individually for each participant at 1-month intervals. Participants were randomized to receive the four active doses in either ascending or descending order (nine participants each). Placebo was scheduled quasi-randomly. During sessions, volunteers used eyeshades and were instructed to direct their attention inward. Volunteers completed questionnaires assessing effects immediately after and 1 month after each session, and at 14 months follow-up.

Results

Psilocybin produced acute perceptual and subjective effects including, at 20 and/or 30 mg/70 kg, extreme anxiety/fear (39% of volunteers) and/or mystical-type experience (72% of volunteers). One month after sessions at the two highest doses, volunteers rated the psilocybin experience as having substantial personal and spiritual significance, and attributed to the experience sustained positive changes in attitudes, mood, and behavior, with the ascending dose sequence showing greater positive effects. At 14 months, ratings were undiminished and were consistent with changes rated by community observers. Both the acute and persisting effects of psilocybin were generally a monotonically increasing function of dose, with the lowest dose showing significant effects.

Conclusions

Under supportive conditions, 20 and 30 mg/70 kg psilocybin occasioned mystical-type experiences having persisting positive effects on attitudes, mood, and behavior. Implications for therapeutic trials are discussed.

Keywords

Psilocybin Dose effects Hallucinogen Entheogen Psychedelic Mystical experience Fear Spiritual Religion Positive psychology Humans