Naloxone-reversible analgesic response to combat-related stimuli in posttraumatic stress disorder. A pilot study.

We tested the hypothesis that exposure to a stimulus resembling the original traumatic event would induce naloxone-reversible analgesia in patients with posttraumatic stress disorder (PTSD). Eight medication-free Vietnam veterans with PTSD and eight veterans without PTSD, matched for age and combat severity, viewed a 15-minute videotape of dramatized combat under naloxone hydrochloride and placebo conditions in a randomized double-blind crossover design. In the placebo condition, the subjects with PTSD showed a 30% decrease in reported pain intensity ratings of standardized heat stimuli after the combat videotape. No decrease in pain ratings occurred in the subjects with PTSD in the naloxone condition. The subjects without PTSD did not show a decrease in pain ratings in either condition. The results are consistent with the induction of opioid-mediated stress-induced analgesia in the patients with PTSD.