, Volume 218, Issue 4, pp 649–665 | Cite as

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

  • Roland R. GriffithsEmail author
  • Matthew W. Johnson
  • William A. Richards
  • Brian D. Richards
  • Una McCann
  • Robert Jesse
Original Investigation



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


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


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.


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.


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.


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



Conduct of this research was supported by grants from the Council on Spiritual Practices, the Heffter Research Institute, and the Betsy Gordon Foundation. Effort for Roland Griffiths, Ph.D. in writing this paper was partially provided by NIH grant RO1DA03889. We thank David Nichols, Ph.D. for synthesizing the psilocybin, Mary Cosimano, M.S.W. for her role as a primary session monitor, Maggie Klinedinst for data management, and Linda Felch, M.A. and Paul Nuzzo, M.A. for statistical analyses. We also thank Larry Carter, Ph.D., Ryan Lanier, Ph.D., Benjamin McKay, Chad Ressig, Ph.D., and Ryan Vandrey, Ph.D. for serving as assistant session monitors. The study was conducted in compliance with United States laws.


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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Roland R. Griffiths
    • 1
    • 2
    Email author
  • Matthew W. Johnson
    • 1
  • William A. Richards
    • 3
  • Brian D. Richards
    • 3
  • Una McCann
    • 1
  • Robert Jesse
    • 4
  1. 1.Department of Psychiatry and Behavioral SciencesJohns Hopkins University School of MedicineBaltimoreUSA
  2. 2.Department of NeuroscienceJohns Hopkins University School of MedicineBaltimoreUSA
  3. 3.Department of PsychiatryJohns Hopkins Bayview Medical CenterBaltimoreUSA
  4. 4.Council on Spiritual PracticesSan FranciscoUSA

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