To examine ethnic differences in pain sensitivity
and relationship of pain tolerance to blood pressure
and neuroendocrine factors.
Fifty-one African Americans
(24 men, 27 women) and 55 people from other ethnic groups (primarily Caucasian; 26 men, 29 women) were tested twice for pain sensitivity
to tourniquet ischemia, thermal heat, and cold pressor tests, once following mental stress and once following rest control. Resting and stress-induced blood pressure
(BP), plasma norepinephrine
(NE), and cortisol
In response to all three pain tests, African Americans
had lower pain tolerance relative to Caucasian/Others after both rest and stress. Only the non–African American group showed the expected inverse relationship between BP and pain sensitivity
. African Americans
had lower cortisol
concentrations at rest and stress and showed blunted NE and systolic BP responses to stress. Only in Caucasians/Others was the relationship seen between higher stress-induced BP, cortisol
, and NE levels and greater pain tolerance.
The results suggest that there are alterations in endogenous pain regulatory mechanisms involving BP, cortisol
, and NE in African Americans
. Such dysregulation may contribute to the greater rate of clinical pain symptoms they experience. It is hypothesized that greater chronic stress in African Americans
may be a contributing factor to the alterations in pain regulation.
ANOVA = analysis of variance; BP = blood pressure; NE = norepinephrine; SBP = systolic blood pressure; SIA = stress-induced analgesia; TSST = Trier Social Stress Test; LC = locus coeruleus.