Plasma tau is negatively correlated with frontal lobe CBF in hypertensive adults on the AD spectrum

Background Hypertension can lead to vascular dementia by causing cerebral hypoperfusion, and it may play a similar role in AD. Hypertensive individuals with AD have poorer cognition than normotensive counterparts (Moonga et al 2017), and CSF tau increases more quickly in at‐risk older adults with hypertension than in those without (Bos et al 2019). We investigated the relationships between cerebral blood flow (CBF), plasma tau and hypertension in two cohorts of older individuals. Methods Participants included 30 cognitively normal (CN), 19 subjective cognitive decline (SCD), 17 mild cognitive impairment (MCI), and 8 AD. Groups were defined by CN/SCD and MCI/AD. Participants had 3D pseudo‐continuous arterial spin label (pCASL) 3T Prisma MRI and plasma tau Simoa assay from the same visit. Multiple regression was used to assess the relationship between CBF and plasma tau on a regional and voxel‐wise basis with age, sex, diagnostic group, and total grey matter as covariates. A replication analysis between CBF from 2D pulsed ASL and plasma tau was completed in an independent sample (11 CN, 4 SCD, 15 MCI, 6 AD). Results Hypertensive individuals had higher plasma tau than normotensive, regardless of diagnostic group (β=0.254, p=0.031), the replicate sample had the same relationship (β=0.320, p=0.086). Global CBF, however, differed by group (CN/SCD > MCI/AD; p