Race Effects on Conditioned Pain Modulation in Youth

Abstract

Race and ethnicity shape the experience of pain in adults, with African Americans typically exhibiting greater pain intensity and evoked pain responsiveness than Non-Hispanic Whites. However, it remains unclear whether there are racial differences in conditioned pain modulation (CPM) and if these are present in youth. CPM refers to a reduction in perceived pain intensity for a test stimulus during application of a conditioning stimulus and may be especially relevant in determining risk for chronic pain. The present study assessed CPM to evoked thermal pain in 78 healthy youth (ages 10 to 17), 51% of whom were African American and 49% were Non-Hispanic White. African-American youth reported lower mean conditioning pain ratings than Non-Hispanic White youth, controlling for mean pre-conditioning pain ratings, which is consistent with stronger CPM. Multilevel models demonstrated stronger CPM effects in African-American than Non-Hispanic White youth, as evident in more rapid within-person decreases in pain ratings during the conditioning phase. These findings suggest that diminished CPM likely does not account for the enhanced responsiveness to evoked thermal pain observed in African-American youth. These results may have implications for understanding racial differences in chronic pain experience in adulthood. Perspective This study evaluated conditioned pain modulation to evoked thermal pain in African-American and Non-Hispanic White youth. Findings could have implications for the development of personalized chronic pain treatment strategies that are informed by race and ethnicity.

(236) Impaired conditioned pain modulation in youth with functional abdominal pain

“…Few evoked pain studies have been conducted in healthy youth [4,26,28,34] and only two have examined CPM [29,42]. Relatively little is known about experimental pain responses in youth with FAP.…”

“…The `test stimulus' for the CPM thermal pain protocol was a thermal pain stimulus delivered by a thermode (30 × 30 mm) applied to the ventral forearm of the participant's non-dominant arm and administered via a computerized Medoc TSA-II Neurosensory Analyzer using commercially available software (TPS-CoVAS version 3.19, Medoc Inc., Ramat Yishay, Israel). As in previously published work [29], the `conditioning stimulus' for the CPM protocol was a Boekel General Purpose Water Bath (Boekel Scientific, Feasterville, PA) maintained at a steady temperature of 46.5°C in accordance with previously-established guidelines [55]. Perceived pain intensity was rated by participants on a 0 to 100 scale (0 = "no pain" and 100 = "worst imaginable pain").…”

“…Recent evidence of mean differences in CPM between girls with and without IBS (d = 0.71) suggests that a minimum of 53 adolescents per group would be necessary to detect CPM effects [52]. Based on evidence of individual differences in pain rating changes across conditioning trials during CPM procedures [29], we examined within-individual changes in pain ratings from the mean pre-conditioning rating across the three conditioning trials. A multilevel model (MLM) was specified using hierarchical linear models (HLM 6) [37] consisting of a within-person (i.e., level-1) sub-model describing how each individual's pain ratings changed over successive trials, and a between-person (i.e., level-2) sub-model describing how these changes varied across individuals [5,39].…”

“…34 Demographic covariates (race, sex, age) were included as predictors of baseline pain ratings. The race X trial interaction (β 12 ) was controlled for, based on evidence of racial differences in CPM in healthy youth [29]. Preliminary analyses examined potential sex and age differences in CPM effects (i.e., the sex X trial and age X trial interactions) and tested whether CPM effects were associated with somatic symptom severity and/or functional disability.…”

“…Diminished CPM (relative to control samples) has been observed in a variety of chronic pain conditions, including fibromyalgia [19,22], temporomandibular disorder [17], and chronic headache [32]. Impaired CPM has also been found in adults with IBS [14,17,31,51] and is linked to greater distress and discomfort in these individuals [15].Few evoked pain studies have been conducted in healthy youth [4,26,28,34] and only two have examined CPM [29,42]. Relatively little is known about experimental pain responses in youth with FAP.…”