Conceptual analysis of mechanisms and methods in psychedelic clinical trial design: a narrative review
Therapeutic Advances in Psychopharmacology July 1, 2026 Martin Krsak, David Sparrow, Bernard Rosner et al.
Clinical trials of psychedelic-assisted therapy face unique challenges beyond those of typical pharmacotherapeutics. The therapeutic container—including preparatory and integrative psychotherapy and supportive dosing sessions—likely affects outcomes, and the therapeutic relationship between subjects and therapists is more impactful than in drug-only trials. The most critical problem is the inability to maintain effective blinding in placebo-controlled settings; all attempted approaches have resulted in significant functional unblinding. This makes it difficult to separate the true therapeutic effect of the psychedelic plus psychotherapy from positive expectancy in active subjects and negative expectancy in placebo subjects. Functional unblinding may be deeply connected to the mechanism of therapeutic action itself. The manuscript discusses advantages and disadvantages of current approaches and proposes conceptual and methodological perspectives.