Cumulative Blood Pressure Exposure During Young Adulthood and Mobility and Cognitive Function in Midlife

Abstract

Background: High blood pressure (BP) is a known risk factor for mobility and cognitive impairment in older adults. This study tested the association of cumulative BP exposure from young adulthood to midlife with gait and cognitive function in midlife. Furthermore, we tested whether these associations were modified by cerebral white matter hyperintensity (WMH) burden.

Methods: We included 191 participants from the CARDIA study (Coronary Artery Risk Development in Young Adults), a community-based cohort of young individuals followed over 30 years. Cumulative BP was calculated as the area under the curve (mm Hg×years) from baseline up to year 30 examination. Gait and cognition were assessed at the year 30 examination. Cerebral WMH was available at year 30 in a subset of participants (n=144) who underwent magnetic resonance imaging. Multiple linear regression models were used to assess the association of cumulative BP exposure with gait and cognition. To test effect modification by WMH burden, participants were stratified at the median of WMH and tested for interaction.

Results: Higher cumulative systolic and diastolic BPs were associated with slower walking speed (both P=0.010), smaller step length (P=0.011 and 0.005, respectively), and higher gait variability (P=0.018 and 0.001, respectively). Higher cumulative systolic BP was associated with lower cognitive performance in the executive (P=0.021), memory (P=0.015), and global domains (P=0.010), and higher cumulative diastolic BP was associated with lower cognitive performance in the memory domain (P=0.012). All associations were independent of socio-demographics and vascular risk factors (body mass index, smoking, diabetes mellitus and total cholesterol). The association between cumulative BP and gait was moderated by WMH burden (interaction P<0.05). However, the relation between cumulative BP and cognitive function was not different based on the WMH burden (interaction P>0.05).

Conclusions: Exposure to higher BP levels from young to midlife is associated with worse gait and cognitive performance in midlife. Furthermore, WMH moderates the association of cumulative BP exposure with gait, but not with cognitive function in midlife. The mechanisms underpinning the impact of BP exposure on brain structure and function must be investigated in longitudinal studies using a life course approach.

Keywords: blood pressure; cognition; gait; middle aged; white matter diseases; young adult.

Figure 1.. Gait at Y₃₀ examination in tertiles of cumulative blood pressure over 30 years.

Bars represent means (standard error) calculated from ANCOVA after adjustment for age, sex, race and height. P values show p for trends from ANCOVA. Abbreviations: SBP: systolic blood pressure and DBP: diastolic blood pressure.

Figure 2.. Cognition at Y₃₀ examination in tertiles of cumulative blood pressure over 30 years.

Bars represent means (standard error) calculated from ANCOVA after adjustment for age, sex, race and education. P values show p for trends from ANCOVA. Abbreviations: SBP: systolic blood pressure and DBP: diastolic blood pressure.

Figure 3.. Association between cumulative blood pressure during young adulthood with gait and cognition at midlife, stratified for those with low and high loads of white matter hyperintensities.

The β represents unstandardized regression coefficients. Gait variables were transformed to z-scores. GVI and step time were multiplied by −1 for consistency in interpretation. All analyses were adjusted for age, sex, race, height or education, smoking status, diabetes prevalence, total cholesterol level and body mass index measured at Y30 examination. p values show p for interaction. WMH was divided in low and high groups at the median of WMH (n=72 per group). Abbreviation: SBP: systolic blood pressure; DBP: diastolic blood pressure; WMH: white matter hyperintensity and GVI: gait variability index.