CSF fibrinogen predicts longitudinal Tau accumulation in cognitively unimpaired older adults.

INTRODUCTION

Blood-brain barrier (BBB) dysfunction is an early feature of Alzheimer's disease (AD). Fibrinogen represents a sensitive marker of BBB leakage, but whether it modifies longitudinal tau progression in cognitively unimpaired (CU) individuals remains unknown.

METHODS

CU older adults underwent clinical evaluation and cerebrospinal fluid (CSF) assessment of fibrinogen, Aβ42, total tau (tTau), phosphorylated tau 181 (pTau181), and YKL-40. Linear regression tested baseline associations. Linear mixed-effects models tested whether baseline fibrinogen predicted longitudinal pTau181 change.

RESULTS

Among 169 CU participants with baseline fibrinogen, 87 had longitudinal pTau181 measurements (mean follow-up 2.5-years). Higher fibrinogen was associated with elevated YKL-40 (β = 0.28, 95% confidence interval [CI] [0.11, 0.45]) but not Aβ42, tTau, or pTau181 at baseline. Baseline fibrinogen modified longitudinal pTau181 trajectories (interaction β = 0.11, 95% CI [0.04, 0.19]), with only participants above the median showing significant pTau181 increases (β = 0.13, 95% CI [0.08, 0.18]).

DISCUSSION: CSF fibrinogen associates cross-sectionally with glial inflammation and predicts accelerated tau accumulation in preclinical AD.