Inflammatory markers and cognition in well-functioning African-American and white elders.
BACKGROUND
Several lines of evidence suggest that inflammatory mechanisms contribute to AD.


OBJECTIVE
To examine whether several markers of inflammation are associated with cognitive decline in African-American and white well-functioning elders.


METHODS
The authors studied 3,031 African-American and white men and women (mean age 74 years) enrolled in the Health, Aging, and Body Composition Study. Serum levels of interleukin-6 (IL-6) and C-reactive protein (CRP) and plasma levels of tumor necrosis factor-alpha (TNFalpha) were measured at baseline; cognition was assessed with the Modified Mini-Mental State Examination (3MS) at baseline and at follow-up. Cognitive decline was defined as a decline of >5 points.


RESULTS
In age-adjusted analyses, participants in the highest tertile of IL-6 or CRP performed nearly 2 points lower (worse) on baseline and follow-up 3MS (p < 0.001 for all) and declined by almost 1 point over the >2 years (p = 0.01 for IL-6 and p = 0.04 for CRP) compared with those in the lowest tertile. After multivariate adjustment, 3MS scores among participants in the highest tertile of IL-6 and CRP were similar at baseline but remained significantly lower at follow-up (p < or = 0.05 for both). Those in the highest inflammatory marker tertile were also more likely to have cognitive decline compared with the lowest tertile for IL-6 (26 vs 20%; age-adjusted odds ratio [OR] = 1.34; 95% CI 1.06 to 1.69) and for CRP (24 vs 19%; OR = 1.41; 95% CI 1.10 to 1.79) but not for TNFalpha (23 vs 21%; OR = 1.12; 95% CI 0.88 to 1.43). There was no significant interaction between race and inflammatory marker or between nonsteroidal anti-inflammatory drug use and inflammatory marker on cognition.


CONCLUSIONS
Serum markers of inflammation, especially IL-6 and CRP, are prospectively associated with cognitive decline in well-functioning elders. These findings support the hypothesis that inflammation contributes to cognitive decline in the elderly.
Yaffe
K
K
Department of Psychiatry, University of California, San Francisco 94121, USA. kyaffe@itsa.ucsf.edu
Lindquist
K
K
Penninx
B W
BW
Simonsick
E M
EM
Pahor
M
M
Kritchevsky
S
S
Launer
L
L
Kuller
L
L
Rubin
S
S
Harris
T
T
D001741:Black or African American / Q000706:statistics & numerical data*; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology; D015415:Biomarkers / Q000032:analysis; D002097:C-Reactive Protein / Q000032:analysis*; D003071:Cognition / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D016013:Likelihood Functions; D008297:Male; D015999:Multivariate Analysis; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D016017:Odds Ratio; D011446:Prospective Studies; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis*; D044465:White People / Q000706:statistics & numerical data*
D015415:Biomarkers; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein