title: Interleukin-6 and C-Reactive Protein Levels and 9-Year Cognitive Decline in Community-Dwelling Older Women: The Women's Health and Aging Study II.
abstract: BACKGROUND
  Elevated inflammation is a proposed mechanism relating chronic diseases to cognitive dysfunction. The objective of this study was to test the hypothesis that greater levels of inflammation, as measured by the proinflammatory cytokine interleukin-6 (IL-6) and C-reactive protein, are associated with faster rates of cognitive decline among cognitively intact community-dwelling older women.
  
  
  METHODS
  We analyzed 336 women from the Women's Health and Aging Study II. Cognitive assessments were performed at baseline and every 18-36 months, and included the following domains: immediate and delayed memory (Hopkins Verbal Learning Test), psychomotor speed (Trail Making Test, Part A), and executive function (Trail Making Test, Part B). Aggregate measures of IL-6 and C-reactive protein, based on the average from visits one and two, were analyzed categorically. Random effects models were employed to test the relationship between tertiles of each inflammatory marker and changes in cognitive domain scores over 9 years.
  
  
  RESULTS
  Moderate and high levels of IL-6 predicted early declines in psychomotor speed by 1.0 connection/min per year. There were no differences in baseline scores or rates of change across tertiles of IL-6 in memory or executive function. No differences were observed across tertiles of C-reactive protein for all cognitive domains.
  
  
  CONCLUSIONS
  Higher levels of serum IL-6 were associated with greater declines in psychomotor speed over 9 years. This finding could suggest that elevated IL-6 may result in microvascular changes that may lead to damage of myelin sheaths that line neuronal axons, leading to decreased neuron propagation and impaired processing speed; however, mechanistic studies are needed to evaluate these hypotheses.
authors.affiliation: Department of Epidemiology, Johns Hopkins University, Baltimore, Maryland. Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Priya
authors.initials: P
authors.lastname: Palta
authors.affiliation: Department of Medicine, Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Qian-Li
authors.initials: QL
authors.lastname: Xue
authors.affiliation: Department of Epidemiology, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Deal
authors.affiliation: Department of Medicine, Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Linda P
authors.initials: LP
authors.lastname: Fried
authors.affiliation: Department of Medicine, Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Walston
authors.affiliation: Department of Mental Health, Johns Hopkins University, Baltimore, Maryland. mcarlso2@jhu.edu.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Carlson
mesh_terms: D000368:Aged; D000375:Aging / Q000097:blood* / Q000523:psychology*; D002097:C-Reactive Protein / Q000378:metabolism*; D003072:Cognition Disorders / Q000097:blood*; D015331:Cohort Studies; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008568:Memory / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D013997:Time Factors
chemical_list: D015850:Interleukin-6; D002097:C-Reactive Protein
keywords: C-reactive protein; Cognitive decline.; Interleukin-6; Psychomotor speed