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Masking Influences: A Systematic Review of Placebo Control and Masking in Psychedelic Studies
Aleksandra Barstowe1, Petri J Kajonius1
1Department of Psychology, Lund University, Lund, Sweden.
Journal of Psychoactive Drugs
|November 6, 2024
Summary
Masking success in psychedelic-assisted therapy trials is often poor, potentially influencing results. Researchers recommend improving blinding methods to ensure treatment efficacy is accurately measured.
Area of Science:
- Psychiatry
- Clinical Psychology
- Pharmacology
Background:
- Psychedelic-assisted therapy shows promise for psychiatric conditions.
- Effective blinding is crucial for placebo-controlled trials but often unevaluated.
Purpose of the Study:
- To systematically review placebo control and masking success in psychedelic-assisted therapy studies.
- To assess the impact of masking on trial outcomes.
Main Methods:
- Systematic review of 9 studies (Jan 2010 - Mar 2023) from 6 databases.
- Inclusion/exclusion criteria applied to select relevant trials.
- Analysis of reported masking success and placebo effect sizes.
Main Results:
- Nearly 78% of studies exhibited poor masking success.
- Large effect sizes were observed in 60% of active placebo and 75% of inactive placebo groups.
- Potential unblinding effects cannot be ruled out.
Conclusions:
- Observed treatment effects may be influenced by inadequate masking, not solely psychedelic efficacy.
- Psilocybin, Ayahuasca, and LSD efficacy requires careful interpretation due to masking issues.
- Future trials need enhanced blinding procedures and alternative designs to control for masking influences.
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