Is there a genuine placebo effect in acute depression treatments? A reassessment of regression to the mean and spontaneous remission.

Abstract

Regression to the mean and spontaneous improvements are rarely considered in interpretations of treatment trials for acute major depression. Here I suggest that regression to the mean and spontaneous remission may account for most improvements seen in placebo groups and also for a large proportion of variance in the acute treatment outcome of both antidepressant pharmacotherapy and psychotherapy. These findings have important implications for the interpretation of active treatments and placebo response in depression trials.