DigitalDrifter
Senior Member (Voting Rights)
This much cited (over 1600 citations) study from 1978 claims to have proven the placebo effect is real.
https://pubmed.ncbi.nlm.nih.gov/80579/
https://pubmed.ncbi.nlm.nih.gov/80579/
The effect of naloxone upon dental postoperative pain was studied to examine the hypothesis that endorphins mediate placebo analgesia. All patients had extraction of impacted mandibular third molars with diazepam, N2O, and local block with mepivacaine. 3 h and 4 h after surgery naloxone or a placebo was given under randomised, double-blind conditions. Pain was evaluated upon a visual analogue scale. Patients given naloxone reported significantly greater pain than those given placebo. Patients given placebo as their first drug was either placebo responders, whose pain was reduced or unchanged, or nonresponders whose pain increased. Naloxone given as a second drug produced no additional increase in pain levels in nonresponders but did increase pain levels of placebo responders. Nonresponders had a final mean pain rating identical to that of responders who received naloxone as their second drug. Thus the enhancement of reported pain produced by naloxone can be entirely accounted for by its effect upon placebo responders. These data are consistent with the hypothesis that endorphin release mediates placebo analgesia for dental postoperative pain.