Cumulative blood pressure load and cognitive decline in older adults: An observational analysis of two large cohorts

Introduction: Cumulative blood pressure metrics may provide greater precision for measuring temporal risk exposure, especially in later life where data are mixed regarding associations of high blood pressure (BP) on cognitive function. We examined the relationship between greater cumulative exposure to high BP in later life and several domains of cognitive function. Methods: Individual cognitive assessment scores and BP measurements in older adults (age ≥70 years) at baseline and over approximately 8 years of follow-up were available in the population-based Canadian Victoria Longitudinal Study (VLS) and Swedish Gothenburg H70 Birth Cohort Studies (H70). Linear mixed models were used to quantify associations between cumulative systolic and diastolic BP and change in cognitive scores. Results: Each additional 100mmHg increase in cumulative BP was related to greater decline in the Rey Auditory Verbal Learning Test (RAVLT) List A, trials 1-5 total score over follow-up: -0.23 (95% confidence interval [CI] -0.32, -0.13) for systolic BP and -0.41 (95%CI -0.58, -0.23) for diastolic BP. Similarly increases cumulative systolic and diastolic BP were related to greater declines Digit Symbol Substitution Task (DSS) scores: -0.59 (95%CI -0.80, -0.38) and -1.04 (95% CI -1.40, -0.67), respectively. There were no associations of cumulative BP and temporal changes in general cognition, other measures of verbal episodic memory, or semantic fluency. Conclusions: Higher cumulative BP is associated with greater declines in RAVLT measured immediate memory span and complex attention, information processing speed and visuospatial scanning in older adults, but the scale of change is small. Additional research is required to further define these relationships and identify opportunities for prevention.