Measuring and appraising placebo effects in clinical trials: contemporary challenges and approaches in psychiatry.
The lancet. Psychiatry May 1, 2026 Joseph J Taylor, Balázs Szigeti, Noah D Silverberg et al.
Placebo effects remain a major paradox in medical research, with more data available from placebo-controlled trials than on any treatment, yet little deep analysis of how they are measured, appraised, and interpreted. This review shifts focus from clinical practice to clinical trials, examining established and emerging approaches for managing placebo effects in randomized controlled trials. It highlights three key challenges in contemporary psychiatric research: blinding and expectancy in psychedelic trials, large placebo responses in interventional psychiatry trials (device or procedure-based treatments), and the implications of overlapping neurobiological mechanisms between placebo effects and psychiatric treatments.