Abstract Details

BP plays an important role in cerebrovascular health and WM integrity with sex specific mechanisms influencing WM pathology. The role of intra-individual BP variability as a contributor to WM dysfunction is unclear, particularly involving motor control regions.

To determine the role of intra-individual blood pressure (BP) change as a contributor to white matter (WM) damage on MRI and to evaluate the impact of these changes on gait speed and imbalance by sex.

We identified 990 participants enrolled in the population-based Mayo Clinic Study of Aging who had at least 2 BP measurements prior to baseline MRI. The Rochester Epidemiology Project was used to capture vascular risk factors and imbalance. We analyzed fractional anisotropy (FA) and mean diffusivity in WM regions associated with motor control. We evaluated the effect of BP changes and identified regions impacted by BP.  Using structural equation models (SEM), we assessed the effect of BP slope on corticospinal tract (CST) FA, and downstream effects on gait speed and imbalance after age and sex effects.

Of 990 participants, 438 (44%) were women. Hypertension was similar between women and men (67% and 70%; p = 0.301).  There was no difference in systolic BP slope and variability between sexes (p =0.411 and p = 0.424).  Gait speed and imbalance were similar between sexes (p = 0.506; p = 0.453).   In linear models predicting CST FA, the only WM region associated with BP slope, a greater change in BP slope (0.0004; p = 0.026) and female sex (0.017; p<0.001) were significant predictors of lower CST FA.  SEMs showed that older age, female sex, and higher BP slope predicted lower CST FA, and lower CST FA predicted lower gait speed and higher odds of imbalance. 

Intra-individual BP slope and variability impact corticospinal tract connectivity with women having increased susceptibility to damage.