title: Moderating effects of moderate-intensity physical activity in the relationship between depressive symptoms and interleukin-6 in primary care patients.
abstract: OBJECTIVE
  To determine whether the relationship between interleukin (IL)-6 and depressive symptoms is moderated by participation in moderate-intensity physical activity in a sample of primary care patients. Elevated inflammation has been associated with a number of poor health outcomes. Depressive symptoms may be related to higher levels of the inflammatory marker IL-6; however, previous findings are inconsistent, possibly due to unidentified moderating factors.
  
  
  METHODS
  A total of 107 participants, aged ≥ 40 years, were recruited in Rochester, New York, in 2006 to 2007. Depressive symptoms were measured by the Center for Epidemiologic Studies Depression Scale-Revised, participation in moderate-intensity physical activity was measured using a modified version of the Community Health Activities Model Program for Seniors Activity Questionnaire for Older Adults, and serum IL-6 concentrations were determined using standard enzyme-linked immunosorbent assay protocols and high-sensitivity, anti-cytokine antibody pairs. A hierarchical multiple regression analysis was conducted.
  
  
  RESULTS
  The correlation between IL-6 and depressive symptoms was nonsignificant (r = .086, p = .40). The association between IL-6 and depressive symptoms was moderated by participation in moderate-intensity physical activity (p = .02). Among those who did not engage in moderate-intensity physical activity, higher levels of depressive symptoms were significantly associated with higher levels of IL-6 (r = .28, p = .05), whereas this association was not significant among those who did participate in moderate-intensity physical activity (r = -.13, p = .38).
  
  
  CONCLUSIONS
  Participation in moderate-intensity physical activity may buffer the risk of higher inflammation often associated with higher levels of depressive symptoms.
authors.affiliation: Department of Psychiatry, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390. chad_rethorst@utsouthwestern.edu
authors.forename: Chad D
authors.initials: CD
authors.lastname: Rethorst
authors.forename: Jan
authors.initials: J
authors.lastname: Moynihan
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Lyness
authors.forename: Kathi L
authors.initials: KL
authors.lastname: Heffner
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Chapman
mesh_terms: D000203:Activities of Daily Living; D003863:Depression / Q000097:blood / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000276:immunology; D015850:Interleukin-6 / Q000097:blood* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D011320:Primary Health Care / Q000706:statistics & numerical data*; D011569:Psychiatric Status Rating Scales; D011795:Surveys and Questionnaires
chemical_list: D015850:Interleukin-6