P219 ASSOCIATION OF 24-HOURS BLOOD PRESSURE VARIABILITY WITH BRAIN MRI REGIONS OF INTEREST FOR ALZHEIMER'S DISEASE

Introduction: Variability in blood pressure (BP) has been associated with Alzheimer's disease (AD). However, it is unclear whether high variability in BP over 24-hours (24-h) is associated with the pre-clinical stage of AD. By examining brain MRI regions that atrophy decades before AD develops, we investigated the association between 24-h BP variability and MRI regions of interest for AD. Methods: We included baseline information of 324 participants aged ≥40 years old from a population-based study who underwent 24-h ambulatory BP monitoring and brain MRI scans. 24-h systolic BP variability was quantified using the average real variability (ARV) index. Brain MRI regions of interest for AD included the superior and middle frontal gyrus, supramarginal, superior, and precuneus gyrus, temporal pole, medial and inferior gyrus, entorhinal cortex, and hippocampus. We performed adjusted linear regression models to evaluate the association between 24-h systolic BP variability and MRI regions of interest for AD. Results: The mean age was 58.8±12.5 and 75.3% (n=244) were women. The mean thickness of MRI regions of interest for AD ranged from 2.12 mm 3 to 4.04 mm 3 . In linear regression models, every +1.85 mmHg increase in 24-h systolic ARV was associated with lower thickness of the superior (adjusted mean mm 3 , -0.10; 95% confidence interval [CI], -0.21 and -0.01) and middle (adjusted-mean, -0.12 mm 3 ; 95% CI, -0.24 and -0.01) frontal gyrus, medial temporal gyrus (adjusted mean, -0.21 mm 3 ; 95% CI, -0.32 and -0.10), entorhinal cortex (adjusted-mean, 0.11 mm 3 ; 95% CI, -0.21 and -0.01), and hippocampus (adjusted-mean, -0.14 mm 3 ; 95% CI, -0.25 and -0.03); analyses also accounted for the 24-h systolic BP level. High 24-h systolic BP level was associated with lower thickness in 3/10 regions of interest for AD (P≤0.029). Conclusions: Elevated 24-h systolic BP variability is associated with thinning of brain MRI regions of interest for AD. Prospective data are needed to examine whether 24-h BP variability associated with thinning in brain MRI regions will increase the risk of AD.