Exploring pain processing differences in Native Americans.


OBJECTIVE: Several chronic pain conditions are more prevalent in Native Americans than in any other group in the United States; however, little has been done to identify factors contributing to this disparity. The study presented here was designed to examine whether there were pain processing differences in Native Americans relative to non-Hispanic White controls. METHODS: Participants were healthy, pain-free Native Americans (n = 22, 8 females) and non-Hispanic Whites (n = 20, 7 females). Pain processing was assessed from electric pain threshold/tolerance, ischemia pain threshold/tolerance, nociceptive flexion reflex threshold (NFR; an electrophysiological measure of spinal nociception), pain ratings of suprathreshold electric stimuli, and temporal summation of pain and NFR (an electrophysiological measure of spinal cord sensitization). The institutional review board approved all procedures. RESULTS: Compared to non-Hispanic Whites, Native Americans had dampened pain perception (higher ischemia pain tolerance, higher electric pain threshold, lower ratings of electric stimuli). Additionally, temporal summation of NFR was reduced in Native Americans, suggesting sensitization was reduced at the spinal level. CONCLUSIONS: Findings suggest Native Americans have dampened pain and pain signaling, perhaps due to overactivation of descending pain inhibition mechanisms. Given research indicating that other ethnic groups at risk for chronic pain (e.g., African Americans) show enhanced pain and enhanced central sensitization on experimental pain measures, chronic pain risk could be different for Native Americans, thus emphasizing the need for different treatment interventions.