The association of blood pressure variability with dementia and cognitive impairment: A systematic review and meta-analysis

Abstract

<p><b>Objective:</b> A body of empirical work demonstrates that high within-individual blood pressure variability (BPV) holds prognostic value to predict stroke and transient ischemic attack. The magnitude of association between BPV and other neurological outcomes remains less clear. We aimed to summarise the current evidence on whether BPV is associated to dementia and cognitive impairment in healthy older adults.</p> <p><b>Design and method:</b> Electronic databases were searched for full-text articles and conference abstracts in English. Prospective and cross-sectional cohort studies or clinical trials in adults without cognitive impairment at baseline were eligible. Measures of BPV included any metric over any duration (i.e. visit-to-visit BPV, day-to-day BPV, 24-hour BPV), but not day-night patterns. Outcomes included: 1. incident dementia, 2. cognitive impairment (change in cognition over time), 3. the combined endpoint of dementia and cognitive impairment, and 4. cognitive function (cross-sectional studies). If the association of mean BP with the study outcome was reported, this was extracted as well, to compare to prognostic ability of BPV with mean BP.</p> <p><b>Results:</b> After screening of the initial search of 2214 references, 40 papers were included. Seven studies assessed incident dementia, 12 assessed cognitive impairment and 23 assessed cognitive function. The majority of studies assessed visit-to-visit BPV (n=23), followed by 24-hour BPV (n=14) and day-to-day BPV (n=3). Increased systolic BPV was associated with the combined endpoint of dementia and cognitive impairment (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.14-1.35), however mean systolic BP was not (OR = 1.13, 95% CI 0.87 to 1.45). There was no evidence of heterogeneity between BPV and mean systolic BP effect sizes (p=0.47 for comparison, I² = 0%). Results for diastolic BP(V) were similar. Meta-analysis for all outcomes will be available in May 2020 at the conference.</p> <p><b>Conclusions:</b> On the basis of the available studies, high fluctuations in systolic BP were associated with cognitive impairment. However, there was large methodological and statistical heterogeneity among studies. To clarify whether BPV is an independent risk factor for dementia and cognitive impairment, future work should involve an individual participant data meta-analysis to overcome heterogeneity in analytical approaches </p>