Blood Pressure Determinants of Cerebral White Matter Hyperintensities and Microstructural Injury: UK Biobank Cohort Study

Small vessel disease and related stroke and dementia risks are linked to aging and hypertension, but it is unclear whether the pulsatile or steady blood pressure (BP) component is more important for the development of macrostructural hyperintensities and microstructural white matter damage. This was a cross-sectional analysis of the UK Biobank cohort study of community-based adults from 22 UK centers. Linear associations were determined between neuroimaging markers (white matter hyperintensity [WMH] volume and diffusion imaging indices) and mean arterial pressure and pulse pressure (PP), both unadjusted and adjusted for age, sex, cardiovascular risk factors, antihypertensive medication, BP source, and assessment center. In 37 041 participants aged 45 to 82 years (53% female), univariable analyses demonstrated that increases in both BP components were associated with greater WMH volume and white matter injury on diffusion indices, with a larger effect for PP (standardized effect size for WMH: mean arterial BP: 0.182 [95% CIs, 0.170–0.193]; PP: 0.285 [95% CIs, 0.274–0.296]). In multivariable analyses, associations with mean arterial pressure remained similar, but associations with PP diminished, reflecting covariance with age and risk factors (standardized effect size for WMH: mean arterial BP: 0.106 [95% CIs, 0.095–0.117]; PP: 0.011 [95% CIs, −0.001 to 0.023]). The synergistic interaction between PP and age increased the effect of age on WMH and diffusion indices. Both macrostructural and microstructural white matter injury had similar associations with the pulsatile and steady components of hypertension, although PP accentuated the relationship between age and white matter damage.