Exploring the association between cardiovagal baroreceptor sensitivity and hippocampal tissue integrity in young and middle-aged adults
Date
2023
Authors
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Publisher
University of Delaware
Abstract
Prior research has investigated the association of cardiovagal baroreceptor sensitivity (BRS) with white matter neuronal integrity and cerebral perfusion using magnetic resonance imaging (MRI) techniques such as diffusion tensor imaging (DTI) and arterial spin labeling (ASL); however, less is known about the association with specific regions of gray matter (i.e, hippocampus) involved in memory formation and recall. MR elastography (MRE) has emerged as a constructive tool for assessing the viscoelastic mechanical properties of the brain which are believed to reflect the microstructural integrity of neuronal tissue. Previous studies have yet to determine whether BRS and hippocampal (HC) stiffness are correlated. Thus, the fundamental aim of this study is to investigate the association between cardiovagal BRS and the viscoelastic properties of the brain, with a sub goal of examining how advanced age affects this association. We hypothesized that there would be a positive relation between cardiovagal BRS and HC viscoelastic properties that strengthens with age, indicating a greater influence of blood pressure control on HC microstructural integrity. Cardiovagal BRS and HC viscoelastic properties were measured in 10 young (25 ± 2 years) and 10 middle-aged adults (55 ± 3 years). As expected, we observed a lower cBRS in the older group compared with young (p≤0.05). There were no significant differences in HC stiffness or damping ratio when comparing between age groups (p=0.69; p=0.56). To test whether age moderates the relation between cBRS and HC properties, we ran a multiple linear regression with age included as a categorical covariate and found that the middle-aged group tends to have a stronger relationship between HC properties and cBRS compared to the young group (p=0.07). In the same cohort, we looked at the association between HC viscoelastic properties and cerebral blood flow (CBF). There was no significant difference in HC stiffness, damping ratio, or CBF between the two age groups (p=0.68, p=0.60, p=0.26). Additional analysis showed that there was no significant relationship between HC viscoelastic properties and CBF (r2=0.02, p=0.57; r2=0.01, p=0.66). Although these results were not significant, future research should investigate the possible association in a larger sample size.
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Keywords
Autonomic function, Brain health, Cerebrovascular function, Arterial spin labeling