Inflammatory markers and the risk of Alzheimer disease - The Framingham study

Objective: To examine whether serum cytokines and spontaneous production of peripheral blood mononuclear cell ( PBMC) cytokines are associated with the risk of incident Alzheimer disease (AD). Methods: We followed 691 cognitively intact community-dwelling participants (mean age 79 years, 62% women) and related PBMC cytokine production ( tertiles of spontaneous production of interleukin 1 [IL-1], IL-1 receptor antagonist, and tumor necrosis factor alpha [ TNF-alpha]) and serum C-reactive protein and interleukin 6 (IL- 6) to the risk of incident AD. Results: Adjusting for clinical covariates, individuals in the top two tertiles (T2 and T3) of PBMC production of IL-1 or the top tertile (T3) of PBMC production of TNF-alpha were at increased risk of developing AD (multivariable-adjusted hazard ratio [HR] for IL- 1 T2 = 2.84, 95% CI 1.09 to 7.43; p = 0.03 and T3 = 2.61, 95% CI 0.96 to 7.07; p = 0.06; for TNF-alpha, adjusted HR for T2 = 1.30, 95% CI 0.53 to 3.17; p = 0.57 and T3 = 2.59, 95% CI 1.09 to 6.12; p = 0.031]) compared with those in the lowest tertile (T1). Interpretation: Higher spontaneous production of interleukin 1 or tumor necrosis factor alpha by peripheral blood mononuclear cells may be a marker of future risk of Alzheimer disease ( AD) in older individuals. These data strengthen the evidence for a pathophysiologic role of inflammation in the development of clinical AD.