Noninvasive Blood-Brain Barrier Imaging in Aging Community Cohorts

Cerebral perfusion is a critical determinant of brain health and cognitive function, and vascular dysfunction contributes to small-vessel disease and neurodegeneration. Multiecho time-encoded arterial spin labeling is an emerging magnetic resonance imaging technique that enables noninvasive quantification of cerebral blood flow (CBF), arterial transit time (ATT), and blood-brain barrier water exchange time (Tex) without exogenous contrast. This study examined how demographic and vascular risk factors influence cerebral hemodynamics and their relation to structural imaging and cognitive scores.

Participants were drawn from 2 community-based cohorts, comprising 527 adults aged 30 to 95 years. All underwent harmonized 3T multiecho arterial spin labeling and structural magnetic resonance imaging, alongside detailed cognitive testing. Linear and logistic regression models evaluated associations between cerebral hemodynamics, age, sex, vascular risk factors, brain structure, and cognition, adjusting for demographic, vascular, and intracranial volume.

Older age was independently associated with lower CBF and Tex and longer ATT, with a nonlinear age-ATT relationship suggesting accelerated change in later life. Males showed lower CBF and Tex and higher ATT than females, independent of age and vascular risk factors. Hypertension and higher blood pressure were associated with lower Tex, reduced CBF, and longer ATT; diabetes was associated with reduced CBF. Longer ATT correlated with smaller gray and hippocampal volumes and greater white matter hyperintensity. Lower Tex was related to higher white matter hyperintensity volume as well as poorer semantic fluency.

Multiecho arterial spin labeling captures blood-brain barrier-related and hemodynamic changes associated with age, sex, and vascular risk factors, supporting its use as a noninvasive imaging biomarker for early cerebrovascular injury relevant to cardiovascular health.