Blood‐brain barrier dysfunction is associated with A/T/N biomarkers and cognition in the aging brain

Age‐associated dysfunction of the blood‐brain barrier results in increased non‐specific permeability of the barrier and “leakage” of blood proteins into the central nervous system (CNS). Over the past decade, fibrinogen, the blood coagulation factor, has been demonstrated to be necessary and sufficient for triggering brain dysfunction and degeneration in model systems and is now serving as a robust biomarker of pathological BBB leakage. Importantly, BBB leakage may be an early pathological feature of the aging brain, instigating the development of neurodegenerative disease pathologies.