Annals of behavioral medicine : a publication of the Society of Behavioral Medicine
-
Controlled Clinical Trial
Expectancy Effects on Conditioned Pain Modulation Are Not Influenced by Naloxone or Morphine.
Recent studies suggest that participant expectations influence pain ratings during conditioned pain modulation testing. The present study extends this work by examining expectancy effects among individuals with and without chronic back pain after administration of placebo, naloxone, or morphine. ⋯ The present findings confirm that expectancy is an important contributor to conditioned pain modulation effects, and therefore significant caution is needed when interpreting findings that do not account for this individual difference. Opioid mechanisms do not appear to be involved in these expectancy effects.