Researcher(s)
- Ryan Hoefer, Human Physiology, University of Delaware
Faculty Mentor(s)
- Christopher Martens, Kinesiology and Applied Physiology, University of Delaware
- Nathan Romberger, Kinesiology and Applied Physiology, University of Delaware
Abstract
Age-related changes in cognitive function and brain structural integrity are associated with worse cardiovascular health, including elevated blood pressure (BP) and increased arterial stiffness. Both BP and arterial stiffness are affected by the autonomic nervous system (ANS). Interestingly, higher heart rate variability (HRV), a common estimate of ANS activity, has been associated with better overall cognitive function. However, few studies have assessed the association between HRV and brain structural integrity. We assessed the age-related associations between autonomic regulation using HRV and brain microstructural integrity using magnetic resonance elastography (MRE). Young (22-29yr; n=10), middle aged (52-60yr; n=10) and older adults (66-79yr; n=9) underwent measurements of supine resting heart rate using an electrocardiogram for 5-12 minutes and MRE to assess whole-brain (WB) stiffness. LabChart’s built-in HRV module was used to measure HRV, including the standard deviation of RR intervals (SDRR) and root mean square of successive differences (RMSSD). We assessed the association between HRV and WB stiffness using Pearson or Spearman’s correlations. Across all age-groups (22-79yr), age was negatively correlated with SDRR (ρ=-0.558, p=0.002), RMSSD (ρ=-0.495, p=0.006), and WB stiffness (ρ=-0.742, p<0.001). WB stiffness trended towards positive correlations with SDRR (ρ=0.331, p=0.080) and RMSSD (ρ=0.276, p=0.147). When separated by age groups, WB stiffness tended to be positively correlated with RMSSD in older adults (r=0.591, p=0.094); however, this relation was weaker or absent in young (r=0.375, p=0.285) and middle-aged adults (r=-0.284, p=0.426). HRV was positively correlated with WB stiffness, suggesting that decreased autonomic control negatively impacts brain stiffness, particularly in older adults. Future studies should seek to explore how other cardiovascular mechanisms impact cognitive decline and brain integrity.