Hostname: page-component-586b7cd67f-dsjbd Total loading time: 0 Render date: 2024-11-23T21:40:56.206Z Has data issue: false hasContentIssue false
  • English
  • Français

Post-acute psychological effects of classical serotonergic psychedelics: a systematic review and meta-analysis

Published online by Cambridge University Press:  04 November 2020

Simon B. Goldberg Open the ORCID record for Simon B. Goldberg [Opens in a new window] ,
Benjamin Shechet ,
Christopher R. Nicholas ,
Chi Wing Ng ,
Geetanjali Deole ,
Zhuofan Chen  and
Charles L. Raison
Simon B. Goldberg*
Affiliation:
Department of Counseling Psychology, University of Wisconsin – Madison, Madison, WI, USA
Benjamin Shechet
Affiliation:
Department of Counseling Psychology, University of Wisconsin – Madison, Madison, WI, USA
Christopher R. Nicholas
Affiliation:
Department of Family Medicine and Community Health, University of Wisconsin – Madison, Madison, WI, USA
Chi Wing Ng
Affiliation:
Department of Counseling Psychology, University of Wisconsin – Madison, Madison, WI, USA
Geetanjali Deole
Affiliation:
Department of Counseling Psychology, University of Wisconsin – Madison, Madison, WI, USA
Zhuofan Chen
Affiliation:
Department of Counseling Psychology, University of Wisconsin – Madison, Madison, WI, USA
Charles L. Raison
Affiliation:
School of Human Ecology, University of Wisconsin – Madison, Madison, WI, USA Usona Institute, Fitchberg, WI, USA
*
Author for correspondence: Simon B. Goldberg, E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Background

Scientific interest in the therapeutic effects of classical psychedelics has increased in the past two decades. The psychological effects of these substances outside the period of acute intoxication have not been fully characterized. This study aimed to: (1) quantify the effects of psilocybin, ayahuasca, and lysergic acid diethylamide (LSD) on psychological outcomes in the post-acute period; (2) test moderators of these effects; and (3) evaluate adverse effects and risk of bias.

Methods

We conducted a systematic review and meta-analysis of experimental studies (single-group pre-post or randomized controlled trials) that involved administration of psilocybin, ayahuasca, or LSD to clinical or non-clinical samples and assessed psychological outcomes ⩾24 h post-administration. Effects were summarized by study design, timepoint, and outcome domain.

Results

A total of 34 studies (24 unique samples, n = 549, mean longest follow-up = 55.34 weeks) were included. Classical psychedelics showed significant within-group pre-post and between-group placebo-controlled effects on a range of outcomes including targeted symptoms within psychiatric samples, negative and positive affect-related measures, social outcomes, and existential/spiritual outcomes, with large between-group effect in these domains (Hedges' gs = 0.84 to 1.08). Moderator tests suggest some effects may be larger in clinical samples. Evidence of effects on big five personality traits and mindfulness was weak. There was no evidence of post-acute adverse effects.

Conclusions

High risk of bias in several domains, heterogeneity across studies, and indications of publication bias for some models highlight the need for careful, large-scale, placebo-controlled randomized trials.

Keywords

AnxietyayahuascadepressionLSDmeta-analysispsilocybinpsychedelicspsychological effects
Type
Review Article
Information
Psychological Medicine , Volume 50 , Issue 16 , December 2020 , pp. 2655 - 2666
Check for updates
Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aday, J. S., Mitzkovitz, C. M., Bloesch, E. K., Davoli, C. C., & Davis, A. K. (2020). Long-term effects of psychedelic drugs: A systematic review. Neuroscience & Biobehavioral Reviews, 113, 179–189. doi: 10.1016/j.neubiorev.2020.03.017.CrossRefGoogle ScholarPubMed
Anderson, B., Danforth, A., Daroff, R., Stauffer, C., Diller, J, & Woolley, J. (2019). Psilocybin-assisted group therapy for demoralization in long-term AIDS survivors. Biological Psychiatry, 85, S182.CrossRefGoogle Scholar
Barrett, F. S., Doss, M. K., Sepeda, N. D., Pekar, J. J., & Griffiths, R. R. (2020). Emotions and brain function are altered up to one month after a single high dose of psilocybin. Scientific Reports, 10(1), 1–14. doi: 10.1038/s41598-020-59282-y.CrossRefGoogle ScholarPubMed
Becker, B. (1988). Synthesizing standardized mean-change measures. British Journal of Mathematical and Statistical Psychology, 41, 257–278.CrossRefGoogle Scholar
Bershad, A. K., Schepers, S. T., Bremmer, M. P., Lee, R., & de Wit, H. (2019). Acute subjective and behavioral effects of microdoses of lysergic acid diethylamide in healthy human volunteers. Biological Psychiatry, 86(10), 792–800. doi: 10.1016/j.biopsych.2019.05.019.CrossRefGoogle ScholarPubMed
Bogenschutz, M. P., Forcehimes, A. A., Pommy, J. A., Wilcox, C. E., Barbosa, P. C. R., & Strassman, R. J. (2015). Psilocybin-assisted treatment for alcohol dependence: A proof-of- concept study. Journal of Psychopharmacology, 29(3), 289–299. doi: 10.1177/0269881114565144.CrossRefGoogle ScholarPubMed
Bonson, K. R. (2018). Regulation of human research with LSD in the United States (1949–1987). Psychopharmacology, 235(2), 591–604. doi: 10.1007/s00213-017-4777-4.CrossRefGoogle Scholar
Bouso, J. C., dos Santos, R. G., Alcázar-Córcoles, MÁ, & Hallak, J. E. (2018). Serotonergic psychedelics and personality: A systematic review of contemporary research. Neuroscience & Biobehavioral Reviews, 87, 118–132. doi: 10.1016/j.neubiorev.2018.02.004.CrossRefGoogle ScholarPubMed
Callaway, J. C., McKenna, D. J., Grob, C. S., Brito, G. S., Raymon, L. P., Poland, R. E., … Mash, D. C. (1999). Pharmacokinetics of Hoasca alkaloids in healthy humans. Journal of Ethnopharmacology, 65(3), 243–256.CrossRefGoogle ScholarPubMed
Carhart-Harris, R. L. (2019). How do psychedelics work? Current Opinion in Psychiatry, 32(1), 16–21. doi: 10.1097/YCO.0000000000000467.CrossRefGoogle ScholarPubMed
Carhart-Harris, R. L., Bolstridge, M., Day, C. M. J., Rucker, J., Watts, R., Erritzoe, D. E., … Nutt, D. J. (2018 a). Psilocybin with psychological support for treatment-resistant depression: Six-month follow-up. Psychopharmacology, 235(2), 399–408. doi: 10.1007/s00213-017-4771-x.CrossRefGoogle ScholarPubMed
Carhart-Harris, R. L., Bolstridge, M., Rucker, J., Day, C. M., Erritzoe, D., Kaelen, M., … Nutt, D. J. (2016 a). Psilocybin with psychological support for treatment-resistant depression: An open-label feasibility study. The Lancet Psychiatry, 3(7), 619–627. doi: 10.1016/ S2215-0366(16)30065-7.CrossRefGoogle Scholar
Carhart-Harris, R. L., Kaelen, M., Bolstridge, M., Williams, T. M., Williams, L. T., Underwood, R., … Nutt, D. J. (2016 b). The paradoxical psychological effects of lysergic acid diethylamide (LSD). Psychological Medicine, 46(7), 1379–1390. doi: 10.1017/S0033291715002901.CrossRefGoogle Scholar
Carhart-Harris, R. L., Leech, R., Williams, T. M., Erritzoe, D., Abbasi, N., Bargiotas, T., … Wise, R. G. (2012). Implications for psychedelic-assisted psychotherapy: Functional magnetic resonance imaging study with psilocybin. The British Journal of Psychiatry, 200(3), 238–244. doi: 10.1192/bjp.bp.111.103309.CrossRefGoogle ScholarPubMed
Carhart-Harris, R. L., Roseman, L., Haijen, E., Erritzoe, D., Watts, R., Branchi, I., & Kaelen, M. (2018 b). Psychedelics and the essential importance of context. Journal of Psychopharmacology, 32(7), 725–731. doi: 10.1177/0269881118754710.CrossRefGoogle Scholar
Cicchetti, D. (1994). Guidelines, criteria, and rules of thumb for evaluating normed and standardized assessment instruments in psychology. Psychological Assessment, 6(4), 284–290.CrossRefGoogle Scholar
Cipriani, A., Furukawa, T. A., Salanti, G., Chaimani, A., Atkinson, L. Z., Ogawa, Y., … Geddes, J. R. (2018). Comparative efficacy and acceptability of 21 antidepressant drugs for the acute treatment of adults with major depressive disorder: A systematic review and network meta-analysis. The Lancet, 391(10128), 1357–1366. doi: 10.1016/ S0140-6736(17)32802-7.CrossRefGoogle ScholarPubMed
Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale, NJ: Erlbaum.Google Scholar
Cooper, H. M., Hedges, L. V., & Valentine, J. C. (2009). The handbook of research synthesis and meta-analysis (2nd ed.). New York: Russell Sage Foundation.Google Scholar
DeCoster, J., Sparks, E. A., Sparks, J. C., Sparks, G. G., & Sparks, C. W. (2015). Opportunistic biases: Their origins, effects, and an integrated solution. American Psychologist, 70(6), 499–514. doi: 10.1037/a0039191.CrossRefGoogle Scholar
Del Re, A. C., & Hoyt, W. T. (2014). MAd: Meta-analysis with mean differences. R package version 0.8–2, http://CRAN.R-project.org/package=MAd.Google Scholar
dos Santos, R. G., Bouso, J. C., Alcázar-Córcoles, MÁ, & Hallak, J. E. (2018). Efficacy, tolerability, and safety of serotonergic psychedelics for the management of mood, anxiety, and substance-use disorders: A systematic review of systematic reviews. Expert Review of Clinical Pharmacology, 11(9), 889–902. doi: 10.1080/17512433.2018.1511424.CrossRefGoogle ScholarPubMed
Foster, E. D., & Deardorff, A. (2017). Open science framework (OSF). Journal of the Medical Library Association, 105(2), 203–206. doi: 10.5195/jmla.2017.88.Google Scholar
Gasser, P., Holstein, D., Michel, Y., Doblin, R., Yazar-Klosinski, B., Passie, T., & Brenneisen, R. (2014). Safety and efficacy of lysergic acid diethylamide-assisted psychotherapy for anxiety associated with life-threatening diseases. The Journal of Nervous and Mental Disease, 202(7), 513–520. doi: 10.1097/NMD.0000000000000113.CrossRefGoogle ScholarPubMed
Giacomelli, S., Palmery, M., Romanelli, L., Cheng, C. Y., & Silvestrini, B. (1998). Lysergic acid diethylamide (LSD) is a partial agonist of D2 dopaminergic receptors and it potentiates dopamine-mediated prolactin secretion in lactotrophs in vitro. Life Sciences, 63(3), 215–222.CrossRefGoogle ScholarPubMed
Goldberg, S. B., Pace, B. T., Nicholas, C. R., Raison, C. L., & Hutson, P. R. (2020). The experimental effects of psilocybin on symptoms of anxiety and depression: A meta- analysis. Psychiatry Research, 284, 1–4. doi: 10.1016/j.psychres.2020.112749.CrossRefGoogle ScholarPubMed
Griffiths, R. R., Johnson, M. W., Carducci, M. A., Umbricht, A., Richards, W. A., Richards, B. D., … Klinedinst, M. A. (2016). Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial. Journal of Psychopharmacology, 30(12), 1181–1197. doi: 10.1177/0269881116675513.CrossRefGoogle ScholarPubMed
Griffiths, R. R., Johnson, M. W., Richards, W. A., Richards, B. D., Jesse, R., MacLean, K. A., … Klinedinst, M. A. (2018). Psilocybin-occasioned mystical-type experience in combination with meditation and other spiritual practices produces enduring positive changes in psychological functioning and in trait measures of prosocial attitudes and behaviors. Journal of Psychopharmacology, 32(1), 49–69. doi: 10.1177/0269881117731279.CrossRefGoogle ScholarPubMed
Griffiths, R. R., Johnson, M. W., Richards, W. A., Richards, B. D., McCann, U., & Jesse, R. (2011). Psilocybin occasioned mystical-type experiences: Immediate and persisting dose- related effects. Psychopharmacology, 218(4), 649–665. doi: 10.1007/s00213-011-2358-5.CrossRefGoogle ScholarPubMed
Griffiths, R. R., Richards, W. A., McCann, U., & Jesse, R. (2006). Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance. Psychopharmacology, 187(3), 268–283. doi: 10.1007/s00213-006-0457-5.CrossRefGoogle ScholarPubMed
Grob, C.S., Danforth, A.L., Chopra, G.S., Hagerty, M., McKay, C.R., Halberstadt, A.L, & Greer, G.R. (2011). Pilot study of psilocybin treatment for anxiety in patients with advanced-stage cancer. Archives of General Psychiatry, 68(1), 71–78.CrossRefGoogle ScholarPubMed
Guerra-Doce, E. (2015). Psychoactive substances in prehistoric times: Examining the archaeological evidence. Time and Mind, 8(1), 91–112. doi: 10.1080/1751696X.2014.993244.CrossRefGoogle Scholar
Guzmán, G. (2008). Hallucinogenic mushrooms in Mexico: An overview. Economic Botany, 62(3), 404–412.CrossRefGoogle Scholar
Harrer, M., Cuijpers, P., Furukawa, T.A, & Ebert, D. D. (2019). Doing Meta-Analysis in R: A Hands-on Guide. https://bookdown.org/MathiasHarrer/Doing_Meta_Analysis_in_R/.Google Scholar
Higgins, J. P. T., & Green, S. (2008). Cochrane handbook for systematic reviews of interventions. London: John Wiley & Sons.CrossRefGoogle Scholar
Higgins, J. P., Thompson, S. G., Deeks, J. J., & Altman, D. G. (2003). Measuring inconsistency in meta-analyses. BMJ, 327(7414), 557–560.CrossRefGoogle ScholarPubMed
Hofmann, A. (1980). LSD: My problem child. New York: McGraw-Hill.Google Scholar
Hoyt, W. T., & Del Re, A. C. (2018). Effect size calculation in meta-analyses of psychotherapy outcome research. Psychotherapy Research, 28, 379–388. doi: 10.1080/10503307.2017.1405171.CrossRefGoogle ScholarPubMed
Johnson, M. W., Garcia-Romeu, A., Cosimano, M. P., & Griffiths, R. R. (2014). Pilot study of the 5-HT2AR agonist psilocybin in the treatment of tobacco addiction. Journal of Psychopharmacology, 28(11), 983–992. doi: 10.1177/0269881114548296.CrossRefGoogle ScholarPubMed
Jungaberle, H., Thal, S., Zeuch, A., Rougemont-Bücking, A., von Heyden, M., Aicher, H., & Scheidegger, M. (2018). Positive psychology in the investigation of psychedelics and entactogens: A critical review. Neuropharmacology, 142, 179–199. doi: 10.1016/j.neuropharm.2018.06.034.CrossRefGoogle ScholarPubMed
Krebs, T. S., & Johansen, PØ (2012). Lysergic acid diethylamide (LSD) for alcoholism: Meta- analysis of randomized controlled trials. Journal of Psychopharmacology, 26(7), 994–1002. doi: 10.1177/0269881112439253.CrossRefGoogle ScholarPubMed
Lovibond, S. H., & Lovibond, P. F. (1995). Manual for the depression anxiety stress scales (2nd. ed.). Sydney, Australia: Psychology Foundation.Google Scholar
Luoma, J. B., Chwyl, C., Bathje, G. J., Davis, A. K., & Lancelotta, R. (2020). A meta-analysis of placebo-controlled trials of psychedelic-assisted therapy. Journal of Psychoactive Drugs, 52(4), 289–299. doi:10.1080/02791072.2020.1769878.CrossRefGoogle Scholar
MacLean, K. A., Johnson, M. W., & Griffiths, R. R. (2011). Mystical experiences occasioned by the hallucinogen psilocybin lead to increases in the personality domain of openness. Journal of Psychopharmacology, 25(11), 1453–1461. doi: 10.1177/0269881111420188.CrossRefGoogle ScholarPubMed
Madsen, M.K., Fisher, P.M., Stenbæk, D.S., Kristiansen, S., Burmester, D., Lehel, S., & Knudsen, G.M. (2020). A single psilocybin dose is associated with long-term increased mindfulness, preceded by a proportional change in neocortical 5-HT2A receptor binding. European Neuropsychopharmacology, 33, 71–80.CrossRefGoogle ScholarPubMed
McKenna, D. J. (2004). Clinical investigations of the therapeutic potential of ayahuasca: Rationale and regulatory challenges. Pharmacology & Therapeutics, 102(2), 111–129.CrossRefGoogle ScholarPubMed
Michaels, T. I., Purdon, J., Collins, A., & Williams, M. T. (2018). Inclusion of people of color in psychedelic-assisted psychotherapy: A review of the literature. BMC Psychiatry, 18(1), 245. doi: 10.1186/s12888-018-1824-6.CrossRefGoogle ScholarPubMed
Moher, D., Liberati, A., Tetzlaff, J., & Altman, D. G., and the PRISMA Group (2009). Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. Annals of Internal Medicine, 151(4), 264–269.CrossRefGoogle ScholarPubMed
Muttoni, S., Ardissino, M., & John, C. (2019). Classical psychedelics for the treatment of depression and anxiety: A systematic review. Journal of Affective Disorders, 258, 11–24. doi: 10.1016/j.jad.2019.07.076.CrossRefGoogle ScholarPubMed
Nicholas, C. R., Henriquez, K. M., Gassman, M. C., Cooper, K. M., Muller, D., Hetzel, S., … Hutson, P. R. (2018). High dose psilocybin is associated with positive subjective effects in healthy volunteers. Journal of Psychopharmacology, 32(7), 770–778. doi: 10.1177/0269881118780713.CrossRefGoogle ScholarPubMed
Nutt, D. J., King, L. A., & Nichols, D. E. (2013). Effects of schedule I drug laws on neuroscience research and treatment innovation. Nature Reviews Neuroscience, 14(8), 577–585.CrossRefGoogle ScholarPubMed
Ott, J. (1999). Pharmahuasca: Human pharmacology of oral DMT plus harmine. Journal of Psychoactive Drugs, 31(2), 171–177.CrossRefGoogle ScholarPubMed
Palhano-Fontes, F., Barreto, D., Onias, H., Andrade, K. C., Novaes, M. M., Pessoa, J. A., … Tófoli, L. F. (2019). Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: A randomized placebo-controlled trial. Psychological Medicine, 49(4), 655–663. doi: 10.1017/S0033291718001356.CrossRefGoogle ScholarPubMed
Preller, K. H., Herdener, M., Pokorny, T., Planzer, A., Kraehenmann, R., Stämpfli, P., … Vollenweider, F. X. (2017). The fabric of meaning and subjective effects in LSD-induced states depend on serotonin 2A receptor activation. Current Biology, 27(3), 451–457. doi: 10.1016/j.cub.2016.12.030.CrossRefGoogle ScholarPubMed
Project MATCH Research Group (1998). Matching alcoholism treatments to client heterogeneity: Project MATCH three-year drinking outcomes. Alcoholism: Clinical and Experimental Research, 22(6), 1300–1311.Google Scholar
R Core Team (2018). R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing. URL https://www.R-project.org/.Google Scholar
Reiche, S., Hermle, L., Gutwinski, S., Jungaberle, H., Gasser, P., & Majić, T. (2018). Serotonergic hallucinogens in the treatment of anxiety and depression in patients suffering from a life-threatening disease: A systematic review. Progress in Neuropsychopharmacology & Biological Psychiatry, 81, 1–10. doi: 10.1016/j.pnpbp.2017.09.012.CrossRefGoogle ScholarPubMed
Reiff, C. M., Richman, E. E., Nemeroff, C. B., Carpenter, L. L., Widge, A. S., & Rodriguez, C. I., … & Work Group on Biomarkers and Novel Treatments, a Division of the American Psychiatric Association Council of Research. (2020). Psychedelics and psychedelic- assisted psychotherapy. American Journal of Psychiatry, 177, 391–410. doi: 10.1176/appi.ajp.2019.19010035.CrossRefGoogle ScholarPubMed
Romeo, B., Karila, L., Martelli, C., & Benyamina, A. (2020). Efficacy of psychedelic treatments on depressive symptoms: A meta-analysis. Journal of Psychopharmacology, 34(10), 1079–1085. doi:10.1177/0269881120919957.CrossRefGoogle ScholarPubMed
Rosenberg, M. S. (2005). The file-drawer problem revisited: A general weighted method for calculating fail-safe numbers in meta-analysis. Evolution, 59(2), 464–468.CrossRefGoogle ScholarPubMed
Rosenthal, R. (1979). The “file drawer problem” and tolerance for null results. Psychological Bulletin, 86(3), 638–641.CrossRefGoogle Scholar
Ross, S. (2018). Therapeutic use of classic psychedelics to treat cancer-related psychiatric distress. International Review of Psychiatry, 30(4), 317–330. doi: 10.1080/09540261.2018.1482261.CrossRefGoogle ScholarPubMed
Ross, S., Bossis, A., Guss, J., Agin-Liebes, G., Malone, T., Cohen, B., … Schmidt, B. L. (2016). Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: A randomized controlled trial. Journal of Psychopharmacology, 30(12), 1165–1180. doi: 10.1177/0269881116675512.CrossRefGoogle ScholarPubMed
Samorini, G. (2019). The oldest archeological data evidencing the relationship of Homo sapiens with psychoactive plants: A worldwide overview. Journal of Psychedelic Studies, 3, 63–80. doi: 10.1556/2054.2019.008.CrossRefGoogle Scholar
Sampedro, .F, de La Fuente Revenga, M., Valle, M., Roberto, N., Domínguez-Clavé, E., Elices, M., & Friedlander, P. (2017). Assessing the psychedelic “after-glow” in ayahuasca users: post-acute neurometabolic and functional connectivity changes are associated with enhanced mindfulness capacities. International Journal of Neuropsychopharmacology, 20(9), 698–711.CrossRefGoogle ScholarPubMed
Sanches, R.F., de Lima Osório, F., dos Santos, .G.R, Macedo, L.R., Maia-de-Oliveira, J.P., Wichert-Ana, L., & Hallak, J.E. (2016). Antidepressant effects of a single dose of ayahuasca in patients with recurrent depression: a SPECT study. Journal of Clinical Psychopharmacology, 36(1), 77–81.CrossRefGoogle ScholarPubMed
Schenberg, E. E. (2018). Psychedelic-assisted psychotherapy: A paradigm shift in psychiatric research and development. Frontiers in Pharmacology, 9, 733. doi: 10.3389/fphar.2018.00733.CrossRefGoogle ScholarPubMed
Schmid, Y., Enzler, F., Gasser, P., Grouzmann, E., Preller, K. H., Vollenweider, F. X., … Liechti, M. E. (2015). Acute effects of lysergic acid diethylamide in healthy subjects. Biological Psychiatry, 78(8), 544–553. doi: 10.1016/j.biopsych.2014.11.015.CrossRefGoogle ScholarPubMed
Schmid, Y., & Liechti, M.E.. (2018). Long-lasting subjective effects of LSD in normal subjects. Psychopharmacology, 235(2), 535–545.CrossRefGoogle ScholarPubMed
Schultes, R. E. (1969). Hallucinogens of plant origin. Science (New York, N.Y.), 163(3864), 245–254.CrossRefGoogle ScholarPubMed
Smigielski, L., Scheidegger, M., Kometer, M., & Vollenweider, F. X. (2019). Psilocybin- assisted mindfulness training modulates self-consciousness and brain default mode network connectivity with lasting effects. NeuroImage, 196, 207–215. doi: 10.1016/j.neuroimage.2019.04.009.CrossRefGoogle ScholarPubMed
Soler, J., Elices, M., Dominguez-Clavé, E., Pascual, J. C., Feilding, A., Navarro-Gil, M., … Riba, J. (2018). Four weekly ayahuasca sessions lead to increases in “acceptance” capacities: A comparison study with a standard 8-week mindfulness training program. Frontiers in Pharmacology, 9, 224. doi: 10.3389/fphar.2018.00224.CrossRefGoogle ScholarPubMed
Soler, J., Elices, M., Franquesa, A., Barker, S., Friedlander, P., Feilding, A., … Riba, J. (2016). Exploring the therapeutic potential of Ayahuasca: acute intake increases mindfulness-related capacities. Psychopharmacology, 233(5), 823–829. doi:10.1007/s00213-015-4162-0.CrossRefGoogle ScholarPubMed
Strassman, R. J., Qualls, C. R., Uhlenhuth, E. H., & Kellner, R. (1994). Dose-response study of N, N-dimethyltryptamine in humans: II. Subjective effects and preliminary results of a new rating scale. Archives of General Psychiatry, 51(2), 98–108.CrossRefGoogle Scholar
Studerus, E., Gamma, A., & Vollenweider, F. X. (2010). Psychometric evaluation of the altered states of consciousness rating scale (OAV). PloS One, 5(8), e12412. doi:10.1371/journal.pone.0012412.CrossRefGoogle Scholar
Studerus, E., Kometer, M., Hasler, F., & Vollenweider, F. X. (2011). Acute, subacute and long- term subjective effects of psilocybin in healthy humans: A pooled analysis of experimental studies. Journal of Psychopharmacology, 25(11), 1434–1452. doi: 10.1177/0269881110382466.CrossRefGoogle ScholarPubMed
Valentine, J. C., Pigott, T. D., & Rothstein, H. R. (2010). How many studies do you need? A primer on statistical power for meta-analysis. Journal of Educational and Behavioral Statistics, 35(2), 215–247. doi: 10.3102/1076998609346961.CrossRefGoogle Scholar
Viechtbauer, W. (2010). Conducting meta-analyses in R with the metafor package. Journal of Statistical Software, 36(3), 1–49.CrossRefGoogle Scholar
Viechtbauer, W., & Cheung, M. W. L. (2010). Outlier and influence diagnostics for meta- analysis. Research Synthesis Methods, 1(2), 112–125. doi: 10.1002/jrsm.11.CrossRefGoogle ScholarPubMed
Vollenweider, F. X., Vollenweider-Scherpenhuyzen, M. F., Bäbler, A., Vogel, H., & Hell, D. (1998). Psilocybin induces schizophrenia-like psychosis in humans via a serotonin-2 agonist action. NeuroReport, 9(17), 3897–3902.CrossRefGoogle Scholar
Wampold, B., & Imel, Z. E. (2015). The great psychotherapy debate: The evidence for what makes psychotherapy work (2nd ed.). New York: Routledge.CrossRefGoogle Scholar
Supplementary material: File

Goldberg et al. supplementary material

Goldberg et al. supplementary material

Download Goldberg et al. supplementary material(File)
File 85.9 KB