Amyloid and Tau Pathology are Associated with Cerebral Blood Flow in a Mixed Sample of Nondemented Older Adults with and without Vascular Risk Factors for Alzheimer’s Disease

Alzheimer’s disease (AD) is the leading cause of dementia in individuals over 65 in the U.S. Prevalence is projected to double by 2050, but current treatments cannot stop the progression of AD. Treatments administered before severe cognitive decline may be effective; identification of biomarkers for preclinical and prodromal stages of AD is therefore imperative. Cerebral blood flow (CBF) is a potential early biomarker for AD; generally, older adults with AD have decreased CBF compared to normally aging peers. Characterization should include the relationships between CBF and AD risk factors and pathologies. We assessed the relationships between CBF quantified by arterial spin labeled MRI, hypertension,APOEε4, and tau and amyloid PET in 77 older adults: cognitively normal, subjective cognitive decline, and mild cognitive impairment. Tau and amyloid aggregation were related to altered CBF, and some of these relationships were dependent on hypertension orAPOEε4 status. Our findings suggest a complex relationship between risk factors, AD pathologies, and CBF that warrants future studies of CBF as a potential early biomarker for AD.