Expectancy Effects in Psychedelic Trials.
Biological psychiatry. Cognitive neuroscience and neuroimaging – May 01, 2024
Source: PubMed
Summary
Positive expectations may significantly influence outcomes in psychedelic therapy, even with microdosing. When participants believe they'll benefit, they often do - highlighting the complex relationship between mind and medicine. Researchers found that proper trial design and blinding procedures are crucial, as the placebo effect can be particularly strong with psychedelics. This understanding helps optimize therapeutic benefits while improving future treatment protocols.
Abstract
Clinical trials of psychedelic compounds like psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltrptamine (DMT) have forced a reconsideration of how nondrug factors, such as participant expectations, are measured and controlled in mental health research. As doses of these profoundly psychoactive substances increase, so does the difficulty in concealing the treatment condition in the classic double-blind, placebo-controlled trial design. As widespread public enthusiasm for the promise of psychedelic therapy grows, so do questions regarding whether and how much trial results are biased by positive expectancy. First, we review the key concepts related to expectancy and its measurement. Then, we review expectancy effects that have been reported in both micro- and macrodose psychedelic trials from the modern era. Finally, we consider expectancy as a discrete physiological process that can be independent of, or even interact with, the drug effect. Expectancy effects can be harnessed to improve treatment outcomes and can also be actively managed in controlled studies to enhance the rigor and generalizability of future psychedelic trials.