Fibrinogen is considered a marker of vascular pathology, indicating a weakened blood-brain barrier, and has a causative role in neuroinflammation and neurodegeneration. Little is known about the relationship between fibrinogen levels and cognitive function in patients with mild cognitive impairment (MCI). We aimed to investigate differences in cognitive profiles according to plasma fibrinogen levels in patients with MCI and the influence of plasma fibrinogen levels on cognitive decline.
This retrospective cohort study included 643 patients with MCI: 323 patients in the high fibrinogen (high fib) group and 320 patients in the low fibrinogen (low fib) group. A multiple linear regression model was performed to compare cognitive test performance between groups. The Cox proportional hazard model was used to analyze the hazard ratio of fibrinogen level for disease progression.
The high fib group demonstrated poorer performance in attention, executive function, and confrontation naming than the low fib group. After adjustment for APOE genotype, the high fib group was associated with poor attention and executive function. After adjustment for vascular risk factors including body mass index, hypertension, diabetes mellitus, dyslipidemia, and smoking history, the high fib group showed declined attention and confrontation naming ability. High fibrinogen levels did not predict disease progression to CDR 1.
High plasma fibrinogen levels were associated with poor performance in attention in patients with MCI, regardless of APOE genotype or vascular risk factors.

The Author(s). Published by S. Karger AG, Basel.