Fibrinogen and risk of dementia: A systematic review and meta-analysis

Background: The aim of this meta-analysis is to evaluate the association of fibrinogen with risk of dementia and its subtypes. Methods: Embase, Pubmed and Web of Science were retrieved systematically up to February 2019. Standard mean difference (SMD) with 95 % confidence intervals was estimated using random-effects models. Results: Sixteen studies involving 3,649 participants were summarized. Patients with all-cause dementia exhibited higher fibrinogen levels than those in non-dementia controls (SMD = 0.90 [0.43;1.36] p < 0.01). Further subgroup analysis revealed a positive association of fibrinogen with vascular dementia (VaD) (SMD = 1.11 [0.45;1.78] p < 0.01) rather than Alzheimer's disease (AD) (SMD = 0.01 [-0.17;0.19]) p = 0.92) and Parkinson's disease dementia (PDD) (SMD = 0.35 [-0.23;0.93] p = 0.24). This correlation was significant in Europeans (SMD = 0.92 [0.34;1.49] p < 0.01), but probably not in Asian based populations (SMD = 1.04 [-0.09;2.17] p = 0.07), and gradually declined with advancing age (60 <= age< 70: SMD = 1.22 [0.38;2.06] p< 0.01; 70 <= age< 80: SMD = 0.29 [0.04;0.53] p = 0.02; age >= 80: SMD = 0.01 [-0.12;0.15] p = 0.84). Conclusions: Plasma fibrinogen is a potential risk factor for all-cause dementia and VaD under the age of 80, and is more obvious in cohorts with people of European descent.