title: African Americans show alterations in endogenous pain regulatory mechanisms and reduced pain tolerance to experimental pain procedures.
abstract: OBJECTIVE
  To examine ethnic differences in pain sensitivity and relationship of pain tolerance to blood pressure and neuroendocrine factors.
  
  
  METHODS
  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 were assessed.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7175, USA.
authors.forename: M Beth
authors.initials: MB
authors.lastname: Mechlin
authors.forename: William
authors.initials: W
authors.lastname: Maixner
authors.forename: Kathleen C
authors.initials: KC
authors.lastname: Light
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Fisher
authors.forename: Susan S
authors.initials: SS
authors.lastname: Girdler
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010146:Pain / Q000208:ethnology / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D012146:Rest; D013315:Stress, Psychological / Q000097:blood / Q000208:ethnology / Q000503:physiopathology; D044465:White People / Q000706:statistics & numerical data
chemical_list: D006854:Hydrocortisone; D009638:Norepinephrine