Advisory Committee Chair
Laurence A Bradley
Advisory Committee Members
Date of Award
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Plasma cortisol concentrations obtained directly after the Trier Social Stress test are negatively associated with subsequent pain tolerances during the cold pressor task (CPT) among healthy non-Hispanic whites (NHWs), but not healthy African Americans (AAs). It is possible frequent exposure to perceived discrimination, a marker of chronic stress, explains this lack of association between cortisol regulation and pain tolerances among AAs. Our aim was to determine if 1) ethnic differences in pain sensitivity during the CPT could be partially explained by differences in cortisol regulation among persons with knee osteoarthritis (OA), 2) perceived discrimination was related to cortisol dysregulation, which was in turn related to greater pain sensitivity among African Americans with knee OA, and 3) the relationship between perceived discrimination and pain sensitivity depends on socioeconomic status (SES). Participants were 91 (47 AA; 44 NHW) community-dwelling adults between the ages of 45 to 85 with symptomatic knee OA. Cortisol was measured at three time points: 1) baseline, 2) immediately after the CPT, and 3) 20 min after the CPT. Although AAs exhibited greater pain sensitivity during the CPT than NHWs, cortisol did not mediate this relationship. However, baseline cortisol was positively associated with pain tolerances (a non-verbal pain behavior) in NHWs, while post-CPT cortisol was negatively associated with pain ratings (a verbal pain behavior) in AAs. Opposite of predictions, perceived discrimination was related to lower pain ratings during the CPT, and cortisol regulation did not help explain this relationship. Finally, the relationship between perceived discrimination and pain ratings was only found among AAs of relatively SES. Post-hoc analyses showed that compared to AAs with relatively low incomes, AAs with relatively high incomes were more likely to report an active coping style toward discrimination. These results suggest that verbal pain reports are important for understanding the relationship between cortisol and pain among AAs. Further, perceived discrimination may serve a protective role for AAs with knee OA, particularly those earning relatively high incomes. Future work is needed to determine if AAs reporting an active coping style toward discrimination also report an active coping style during exposure to noxious stimulation.
Herbert, Matthew, "Cortisol Regulation, Perceived Discrimination, and Ethnic Differences in Pain Responses among Persons with Knee Osteoarthritis" (2015). All ETDs from UAB. 1921.