title: Post-menopausal Women Exhibit Greater Interleukin-6 Responses to Mental Stress Than Older Men.
abstract: Acute stress triggers innate immune responses and elevation in circulating cytokines including interleukin-6 (IL-6). The effect of sex on IL-6 responses remains unclear due to important limitations of previous studies.
  
  
  
  The purpose of this study was to examine sex differences in IL-6 responses to mental stress in a healthy, older (post-menopausal) sample accounting for several moderating factors.
  
  
  
  Five hundred six participants (62.9 ± 5.60 years, 55 % male) underwent 10 min of mental stress consisting of mirror tracing and Stroop task. Blood was sampled at baseline, after stress, and 45 and 75 min post-stress, and assayed using a high sensitivity kit. IL-6 reactivity was computed as the mean difference between baseline and 45 min and between baseline and 75 min post-stress. Main effects and interactions were examined using ANCOVA models.
  
  
  
  There was a main effect of time for the IL-6 response (F 3,1512 = 201.57, p = <.0001) and a sex by time interaction (F 3,1512 = 17.07, p = <.001). In multivariate adjusted analyses, IL-6 reactivity was significantly greater in females at 45 min (M = 0.37 ± 0.04 vs. 0.20 ± 0.03 pg/mL, p = .01) and at 75 min (M = 0.57 ± 0.05 vs. 0.31 ± 0.05 pg/mL, p = .004) post-stress compared to males. Results were independent of age, adiposity, socioeconomic position, depression, smoking and alcohol consumption, physical activity, statin use, testing time, task appraisals, hormone replacement, and baseline IL-6. Other significant predictors of IL-6 reactivity were lower household wealth, afternoon testing, and baseline IL-6.
  
  
  
  Healthy, post-menopausal females exhibit substantially greater IL-6 responses to acute stress. Inflammatory responses if sustained over time may have clinical implications for the development and maintenance of inflammatory-related conditions prevalent in older women.
authors.affiliation: Department of Medical and Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA. endrighi@bu.edu.|Division of Behavioral Science Research, Department of Health Policy and Health Services Research, Boston University, Henry M. Goldman School of Dental Medicine, 560 Harrison Ave, 3rd floor, Boston, MA, 02118, USA. endrighi@bu.edu.
authors.forename: Romano
authors.identifier: 0000-0002-9272-5513
authors.initials: R
authors.lastname: Endrighi
authors.affiliation: National Centre Sport and Exercise Medicine, Loughborough University, Loughborough, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Hamer
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Steptoe
mesh_terms: D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D012727:Sex Characteristics; D013315:Stress, Psychological / Q000097:blood
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6
keywords: Interleukin-6; Mental stress; Pro-inflammatory reactivity; Sex