Midlife Hemostasis Measures, 20-Year Cognitive Decline, and Incident Dementia.

BACKGROUND AND OBJECTIVES: Blood concentrations of hemostatic factors affect thrombosis and bleeding diathesis and may contribute to cognitive impairment through modifiable vascular pathologies. Whether hemostasis, assessed in middle age, is associated with late-life cognitive impairment remains largely unknown in a community-dwelling population. METHODS: Using data from 14,128 participants with cognitive function measurements in 1990-1992 from the Atherosclerosis Risk in Communities study, we assessed the associations of hemostasis measures with 20-year changes in cognitive performance and incident dementia. Activated partial thromboplastin time (aPTT) and level of fibrinogen, von Willebrand factor (VWF), factor VIII, factor VII, factor XI, d-dimer, and soluble thrombomodulin were measured in 1987-1989 or 1993-1995. Hemostasis measures were categorized into quintiles, with the lowest quintile indicating low coagulability. Cognitive performance was characterized using a combined z-score from 3 tests (that is, delayed word recall test [DWRT], digit symbol substitution [DSST], and word fluency test [WFT]), assessed in 1990-1992, 1996-1998, and 2011-2013. Dementia was determined either from in-person evaluations or using dementia surveillance through 2017. Mixed-effects models and Cox proportional hazards models were used to assess cognitive trajectories and risk of dementia, respectively. RESULTS: Among 12,765 participants with hemostasis measures in 1987-1989, who were aged 47-70 years at the first cognitive assessment, we observed significant trends of shorter aPTT (p for trend <0.001; difference in 20-year cognitive decline for fifth vs first quintile [Q5 vs Q1]: -0.104 [95% CI -0.160 to -0.048]) and higher levels of factor VII (p < 0.002; Q5 vs Q1: -0.085 [-0.142, -0.028]) and factor VIII (p = 0.033; Q4 vs Q1: -0.055 [-0.111, -0.000]) with greater 20-year cognitive declines. The associations with the decline in DSST were stronger than those with the decline in WFT or DWRT. Consistently, shorter aPTT and higher factor VIII levels were associated with higher dementia risk with HRs for Q5 vs Q1 of 1.23 (95% CI 1.07 to 1.42) and 1.17 (1.01-1.36), respectively, and p for trend of 0.008 and 0.024, respectively. DISCUSSION: Overall, our study found consistent trend associations of aPTT and factor VIII measured in midlife with cognitive decline and incident dementia over 20 years, likely driven by vascular pathologies.