The association between long term blood pressure variability with incident dementia and cognitive impairment: A systematic review and meta‐analysis

Abstract

AbstractBackgroundDementia cases continues to grow in the era of ageing population, with its number approaching 50 million. Accumulating evidence has shown that high blood pressure increases the risk of dementia and cognitive decline. In recent decades, some studies demonstrate that blood pressure variability (BPV) may contribute to cognitive decline and incident dementia independent of the blood pressure level. However, due to the inconsistence of statistical results and clinical methodology, the magnitude of this relationship remains ambiguous. A clear understanding of the role of BPV in dementia may shed light to etiology and early prevention of dementia. This study aims to assess the association between BPV with incident dementia and cognitive impairment.MethodWe searched MEDLINE, Embase, PsycINFO, CINAHL and Web of Science from December 2020 for articles describing trials, retrospective and prospective cohort studies in adults that assessed the association of long‐term BPV (measured through clinic blood pressure monitoring) with incident dementia and cognitive impairment. 5681 papers were identified and eventually 12 articles with full text and 3 abstracts with enough information were included in the quantitative analysis. Of these 15 studies, 2 articles report both dementia and cognitive decline or dysfunction as outcomes, while 5 studies report dementia as an outcome and 8 studies report cognitive decline or dysfunction.ResultHazard Ratio and linear regression coefficient were converted to a standardized one. We found that increased long‐term variability in systolic blood pressure was associated with higher risk of all‐cause dementia [pooled standardized HR of 1.1 (95%CI, 1.01, 1.19)]. Compared to people in lower BPV group, people in higher BPV group was 1.17 times more likely to develop dementia [pooled HR 1.17 (95%CI,1.12, 1.22)]. Cognitive decline was associated with higher SBPV [pooled linear coefficient for MMSE score is ‐0.11(95%CI, ‐0.17, ‐0.05)],which means MMSE score decreases by 0.11 per SD increase in SBPV.ConclusionOur findings suggested that higher long‐term blood pressure variability increases both the risk for incident dementia and cognitive decline.