Background and Purpose--Vascular and inflammatory factors may play an important role in the pathogenesis of dementia. Studies reported an association between plasma levels of inflammation markers and the risk of dementia. Both fibrinogen and C-reactive protein are considered inflammatory markers. Fibrinogen also has important hemostatic properties. We investigated the association of fibrinogen and C-reactive protein with dementia.

Methods--The study was based on the prospective population-based Rotterdam Study. Fibrinogen was measured in a random sample of 2835 persons. High-sensitivity C-reactive protein was measured in the total cohort of 6713 persons. We identified 395 incident dementia cases during follow-up (mean, 5.7 years). We estimated the associations of fibrinogen and C-reactive protein with dementia using Cox proportional hazard models.

Results--Persons with higher levels of fibrinogen had an increased risk of dementia. The hazard ratio for dementia per SD increase of fibrinogen was 1.26 (95% CI, 1.11 to 1.44), adjusted for age and gender, and 1.30 (95% CI, 1.13 to 1.50) after additional adjustment for cardiovascular factors and stroke. For Alzheimer disease, the adjusted hazard ratio was 1.25 (95% CI, 1.04 to 1.49), and for vascular dementia it was 1.76 (95% CI, 1.34 to 2.30). High levels of C-reactive protein were not associated with an increased risk of dementia.

Conclusions--High fibrinogen levels were associated with an increased risk of both Alzheimer disease and vascular dementia, but levels of C-reactive protein were not. This suggests that the increased risk of dementia associated with fibrinogen is because of the hemostatic rather than the inflammatory properties of fibrinogen.