Placebo-controlled trials of MDMA and classical psychedelics like psilocybin, LSD, and DMT for neuropsychiatric disorders have increased, but their success depends on trial design, control conditions, and blinding. Without appropriate controls, placebo and expectation effects are hard to separate from medication effects. This paper explores the neurobiology of placebo and expectation effects and methodological considerations for selecting suitable control conditions, examining advantages and disadvantages of various options and proposing new directions to enhance trial validity and regulatory science.
Expectations—what patients believe will happen—can powerfully shape the outcomes of psychedelic drug therapy. The article discusses how these beliefs interact with the pharmacological effects of psychedelics, potentially amplifying or diminishing therapeutic benefits. It suggests that managing expectations through preparation and the therapeutic setting may be as important as the drug itself. The authors argue that understanding this interplay is crucial for designing effective treatments and for interpreting clinical trial results.