Objectives: To investigate whether circulating acute-phase brain-derived tau (BD-tau) is associated with functional outcome after ischemic stroke.
Methods: Plasma tau was measured by a novel assay that selectively quantifies BD-tau in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which includes adult cases with ischemic stroke and controls younger than 70 years, and in an independent cohort of adult cases of all ages (SAHLSIS2). Associations with unfavorable 3-month functional outcome (modified Rankin scale score >2) were analyzed by logistic regression. Various stratified and sensitivity analyses were performed, for example, by age, stroke severity, recanalization therapy, and etiologic subtype.
Results: This study included 454 and 364 cases from the SAHLSIS and SAHLSIS2, with a median age of 58 and 68 years, respectively. Higher acute BD-tau concentrations were significantly associated with increased odds of unfavorable outcome after adjustment for age, sex, day of blood draw, and stroke severity (NIH stroke scale score) in both cohorts (OR per doubling of BD-tau: 2.9 [95% CI 2.2-3.7], P = 1 × 10-15 and 1.8 [1.5-2.2], P = 7 × 10-9, respectively). The association was consistent in the different stratified and sensitivity analyses.
Discussion: BD-tau is a promising blood-based biomarker of ischemic stroke outcomes, and future studies in larger cohorts are warranted.