title: Self-rated health and interleukin-6: Longitudinal relationships in older adults.
abstract: BACKGROUND
  Both self-rated health (SRH) and inflammation are implicated in chronic diseases and premature mortality. Better SRH is associated with lower proinflammatory cytokines, but there is little evidence about whether this relationship is more stable or dynamic.
  
  
  OBJECTIVE
  To study the between- and within-person associations between SRH and IL-6.
  
  
  METHODS
  Older adults (N=131; Mage=75 years) rated their health and provided blood samples for analysis of IL-6 at separate occasions every 6 months over a period up to 5 years. Age, sex, BMI, neuroticism, and statin use were examined as covariates in multilevel models.
  
  
  RESULTS
  In bivariate models, better SRH, lower BMI, younger age, and female sex correlated with lower IL-6. In multilevel models, stable SRH (between-person differences; p<.001) but not dynamic SRH (within-person changes; p=.93) correlated with IL-6. The stable relationship persisted with demographic and health covariates in the model.
  
  
  CONCLUSIONS
  Better stable SRH but not dynamic SRH was robustly associated with lower IL-6 among older adults, lending support to previous cross-sectional findings on the relation between inflammatory markers and SRH. The findings suggest that trait-like mechanisms, rather than changes over a time scale of 6-month waves, govern this association. To further investigate the mechanisms behind the SRH-IL-6 association, studies with different measurement frequencies, higher within-person variability, and experimental approaches are warranted.
authors.affiliation: Stress Research Institute, Stockholm University, 106 91 Stockholm, Sweden; Department of Neuroscience, Psychiatry, Uppsala University, Uppsala, Sweden. Electronic address: filip.arnberg@su.se.
authors.forename: Filip K
authors.initials: FK
authors.lastname: Arnberg
authors.affiliation: Stress Research Institute, Stockholm University, 106 91 Stockholm, Sweden; Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm, Sweden. Electronic address: mats.lekander@su.se.
authors.forename: Mats
authors.initials: M
authors.lastname: Lekander
authors.affiliation: Department of Psychology, University of Kentucky, 125 Kastle Hall, Lexington, KY 40506-0044, United States. Electronic address: moreyj@tncc.edu.
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Morey
authors.affiliation: Department of Psychology, University of Kentucky, 125 Kastle Hall, Lexington, KY 40506-0044, United States. Electronic address: segerstrom@uky.edu.
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: Segerstrom
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001290:Attitude; D002908:Chronic Disease; D016207:Cytokines / Q000032:analysis; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006304:Health Status; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D057566:Self Report
chemical_list: D016207:Cytokines; C508600:IL6 protein, human; D015850:Interleukin-6
keywords: Cytokines; Interleukin-6; Longitudinal study; Self-rated health