Cerebral blood flow, tau imaging, and memory associations in cognitively unimpaired older adults.

ABSTRACT

Objective: Cerebral blood flow (CBF) has been independently linked to cognitive impairment and traditional Alzheimer's disease (AD) pathology (e.g., amyloid-beta [Aß], tau) in older adults. However, less is known about the possible interactive effects of CBF, Aß, and tau on memory performance. The present study examined whether CBF moderates the effect of Aß and tau on objective and subjective memory within cognitively unimpaired (CU) older adults. Methods: Participants included 54 predominately white CU older adults from the Alzheimer's Disease Neuroimaging Initiative. Multiple linear regression models examined meta-temporal CBF associations with (1) meta-temporal tau PET adjusting for cortical Aß PET and (2) and cortical Aß PET adjusting for tau PET. The CBF and tau meta region was an average of 5 distinct temporal lobe regions. CBF interactions with Aß or tau PET on memory performance were also examined. Covariates for all models included age, sex, education, pulse pressure, APOE-ε4 positivity, and imaging acquisition date differences. Results: CBF was significantly negatively associated with tau PET (t = -2.16, p = .04) but not Aß PET (t = 0.98, p = .33). Results revealed a CBF by tau PET interaction such that there was a stronger effect of tau PET on objective (t = 2.51, p = .02) and subjective (t = -2.67, p = .01) memory outcomes among individuals with lower levels of CBF. Conclusions: Cerebrovascular and tau pathologies may interact to influence cognitive performance. This study highlights the need for future vascular risk interventions, which could offer a scalable and cost-effective method for AD prevention.