Abstract
Blood-brain barrier (BBB) dysfunction is recognized as an early step in the development of Alzheimer's disease and related dementias (ADRD). Biomarkers are needed to monitor BBB integrity over time, better understand the role of the BBB in neurodegeneration, potentially help define long-term ADRD risk, and monitor effects of therapeutics. In this review, we discuss the current biomarkers used to detect human BBB dysfunction in the context of cognitive decline and dementia. We also discuss promising candidate fluid biomarkers to detect BBB dysfunction in blood. HIGHLIGHTS: BBB permeability occurs during normal aging and is further exacerbated in ADRD. In this review, we discuss in vivo imaging and CSF biomarkers of BBB dysfunction currently used in the setting of aging and ADRD in humans. We also review promising candidate blood-based biomarkers that may represent BBB dysfunction.