Plasma phosphorylated tau 181, vascular risk factors, and cognition in elderly Hispanics

BackgroundCerebrovascular risk factors, a group of conditions that reduce or disrupt blood flow to the brain, often occur with Alzheimer's disease (AD) and may contribute to the pathogenesis and cognitive decline. Hispanic individuals are at increased risk of vascular risk factors compared to non-Hispanic white counterparts.ObjectiveWe examined associations among vascular risk factors, including hypertension, diabetes, history of heart disease, and history of stroke, with plasma phosphorylated tau-181 (P-tau181) and cognition.MethodsWe pooled data from 2159 two cohorts of older Hispanic adults. Vascular risk factors were self-reported. Plasma P-tau181 was measured using standardized protocols. Linear regression and mediation models assessed associations among vascular risk, P-tau181, and global cognition, stratified by cognitive status.ResultsOverall, P-tau181 was significantly associated with vascular risk factors and inversely associated with cognitive function. However, vascular risk factors were not independently associated with cognition. Among cognitively unimpaired individuals, vascular risk factors mediated the association between P-tau181 and cognition, while in cognitively impaired individuals, P-tau181 was strongly and independently associated with cognition, without mediation by vascular risk factors.ConclusionsAmong elderly without dementia, vascular risk factors mediate the association between P-tau181 and cognition. However, among individuals with dementia there is no mediation, suggesting that the association between P-tau181 with dementia is independent of cerebrovascular pathology.