Nonplussed by placebos: A response to Colloca and Barsky (2020)

In a recent review published in the New England Journal of Medicine (Placebo and Nocebo Effects), Colloca and Barsky concluded that “Placebo and nocebo effects are powerful, pervasive, and common in clinical practice” and that “Strategies to promote placebo effects and to prevent nocebo effects can improve therapeutic outcomes…” The review cites a substantial amount of impressive neurological, mechanistic research supporting this assertion, much of it led by the authors. However, the review also included a number of problematic statements about the design and interpretation of clinical trials that substantially undercut the authors’ conclusions...