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Overcoming blinding confounds in psychedelic randomized controlled trials using biomarker driven causal mediation
1School of Pharmacy, The University of Auckland, Auckland, New Zealand.
Expert Review of Clinical Pharmacology
|November 10, 2023
Summary
Psychedelic therapies show promise for mental health, but trial results may be inflated by expectancy effects. Causal mediation analysis with biomarkers is proposed to confirm efficacy and establish clear treatment pathways before approval.
Area of Science:
- Psychiatry
- Clinical Psychology
- Pharmacology
Background:
- Psychedelic-assisted therapies are gaining interest for mental health conditions.
- Initial randomized controlled trials (RCTs) show positive outcomes.
- Expectancy effects due to participant and personnel de-blinding may inflate effect sizes in psychedelic RCTs.
Purpose of the Study:
- To introduce causal inference concepts for RCTs.
- To propose causal mediation analysis using biomarkers for psychedelic RCTs.
- To address the need for establishing clear causal pathways for psychedelic therapy efficacy.
Main Methods:
- Introduction to causal inference, assumptions, and confounders in RCTs.
- Proposal of causal mediation analysis with objectively measured biomarkers.
- Graphical illustrations of causal pathways.
Main Results:
- Expectancy effects can inflate effect sizes in psychedelic RCTs due to de-blinding.
- Causal mediation analysis can identify causal pathways even with de-blinding.
- Biomarker-based analysis can increase confidence in the mechanistic basis of psychedelic therapies.
Conclusions:
- Psychedelic therapies should not be approved as licensed medicines until causal pathways are clearly established.
- Potential risks of premature approval include expansion based on low-quality evidence and changing efficacy over time.
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