Do Endorphins Mediate Placebo Analgesia? A Critical Commentary on One of the Seminal Papers.

There are only few experimental studies that assess the hypothesis that placebo analgesia is mediated by endogenous opioids. One of these studies [Grevert P, Albert LH, Goldstein A: Partial antagonism of placebo analgesia by naloxone. Pain 1983;16:129-143] had a rather complicated design and data presentation. In this commentary we attempt to clarify the experimental design of that study. Based on a clearer understanding of the study procedures and data analysis we ropose some alternative interpretations of the results.