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Cited by 324Psychedelics and Drug StudiesPain Management and Placebo EffectStatistical Methods in Clinical Trials

The DOI matches its Crossref record; 128 of the 128 references it cites were found in a registry or an index.

Blinding and expectancy confounds in psychedelic randomized controlled trials

Muthukumaraswamy, Suresh D., Forsyth, Anna, Lumley, Thomas·2021·Expert Review of Clinical Pharmacology
DOI 10.1080/17512433.2021.1933434
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Abstract

Introduction: There is increasing interest in the potential for psychedelic drugs such as psilocybin, LSD and ketamine to treat several mental health disorders, with a growing number of randomized controlled trials (RCTs) being conducted to investigate the therapeutic effectiveness of psychedelics.Areas covered: We review previous literature on expectancy effects and blinding in the context of psychedelic RCTs – literature which strongly suggest that psychedelic RCTs might be confounded by de-blinding and expectancy. We conduct systematic reviews of psychedelic RCTs using Medline, PsychInfo and EMBASE (Jan 1990 – Nov 2020) and show that currently reported psychedelic RCTs have generally not reported pre-trial expectancy, nor the success of blinding procedures.Expert opinion: While psychedelic RCTs have generally shown promising results, with large effect sizes reported, we argue that treatment effect sizes in psychedelic RCTs are likely over-estimated due to de-blinding of participants and high levels of response expectancy. We suggest that psychedelic RCTs should routinely measure de-blinding and expectancy. Careful attention should be paid to clinical trial design and the instructions given to participants to allow these confounds to be reduced, estimated and removed from effect size estimates. We urge caution in interpreting effect size estimates from extant psychedelic RCTs.

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Citations

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Research works printed but not linked: 15

  1. Grinspoon L., 1979, Psychedelic drugs reconsidered/Lester Grinspoon & James B. Bakalar
  2. Hoffmann A, 2013, LSD: my problem child
  3. Kirsch I, 2001, Adv Mind Body Med, 17
  4. Ader R, 2001, Adv Mind Body Med, 17
  5. Greene PJ, 2001, Adv Mind Body Med, 17
  6. Bergmann JF, 1994, Clin Trials Metaanal, 29, 41
  7. ICH Harmonised Tripartite Guideline, 1999, Stat Med, 18, 1905
  8. Caddy C, 2015, Cochrane Database Syst Rev, 23, Cd011612
  9. Sumner R, McMillan R, Spriggs M, et al. Ketamine enhances visual sensory evoked potential LTP in patients with major depressive disorder. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging 2019;In press. · DOI
  10. Straus SE, 2018, Evidence-based medicine E-book: how to practice and teach EBM
  11. Sumner RL, 2021, J Psychopharmacol, 026988112199832
  12. Canuso C, 2019, Neuropsychopharmacology, 44, 454
  13. Doblin R, 1991, J Transpersonal Psychol, 23, 1
  14. Davis AK, 2020, JAMA Psychiatry
  15. Holze F, 2020, Neuropsychopharmacology

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Metadata

Authors
Muthukumaraswamy, S. D., Forsyth, A., & Lumley, T.
Affiliations
University of Auckland (NZ)
Corresponding author
Muthukumaraswamy, Suresh D.
ORCID
Venue
Expert Review of Clinical Pharmacology
Publisher
Informa UK Limited
Published
2021-08-26
Volume
14
Issue
9
Pages
1133-1152
ISSN
  • 1751-2433 (ISSN-L)
  • 1751-2441
DOI
10.1080/17512433.2021.1933434
OpenAlex
W3164618783
Cited by
324
References
128
Citations by year
2026: 57 · 2025: 75 · 2024: 81 · 2023: 61 · 2022: 42 · 2021: 8
FWCI
6.38
Type
journal article
Language
en
Open access
closed
Locations
  • Expert Review of Clinical Pharmacology (publishedVersion)
  • PubMed (publishedVersion)
Funders
Health Research Council of New Zealand
Topics
  • Social Sciences › Psychology › Clinical Psychology › Psychedelics and Drug Studies
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Pain Management and Placebo Effect
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
Keywords
psychedelics, blinding, response expectancy, confounding, psilocybin, LSD, ketamine, effect size overestimation, trial design, mental illness
MeSH terms
Mental Disorders, Hallucinogens, Humans, Ketamine, Lysergic Acid Diethylamide, Psilocybin, Research Design, Confounding Factors, Epidemiologic, Randomized Controlled Trials as Topic

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