Late-life longitudinal blood pressure trajectories as predictor of dementia

Allen T C Lee,Ruby S Y Lee,Helen F K Chiu,Wai C Chan,Marcus Richards,Linda C W Lam,Ada W T Fung

doi:10.1038/s41598-022-05680-3

Abstract

While hypertension is widely recognized as a risk factor for dementia, few observational studies and clinical trials fully accounted for the effect of age on blood pressure (BP) changes prior to dementia onset. In this territory-wide population-based longitudinal study of 16,591 community-living dementia-free older adults, we followed their BP and cognitive status and tested if loss of longitudinal increase in BP in late life was associated with higher dementia risk in 6 years, with consideration of the confounding effects of hypertension, hypotension, BP variability, and other health problems and behaviours and, in the data analysis, exclusion of individuals who developed dementia within 3 years after baseline to minimize risk of reverse causality. Over 72,997 person-years of follow-up, 1429 participants developed dementia. We found that loss of longitudinal increase in systolic BP (defined as SBP increased by either < 10 mmHg or 10%) from baseline to Year 3 was independently associated with higher risk of incident dementia at Years 4 to 6 (adjusted OR 1.22, 95% CI 1.02–1.45, p = 0.03; adjusted OR 1.24, 95% CI 1.03–1.50, p = 0.02; respectively). Our findings suggest that late-life SBP trajectory changes might independently predict dementia onset and highlight the importance of including longitudinal BP monitoring in dementia risk assessment.

Highlights

While hypertension is widely recognized as a risk factor for dementia, few observational studies and clinical trials fully accounted for the effect of age on blood pressure (BP) changes prior to dementia onset
To address this knowledge gap, we conducted a large-scale longitudinal territory-wide population-based study and examined the risk of incident dementia across different Systolic blood pressure (SBP) and Diastolic blood pressure (DBP) trajectories in late life, while taking into consideration the effects of hypertension, hypotension, BP variability, and other potential confounding factors including sociodemographics, health problems and lifestyle behaviours, which themselves have already been shown to increase the risk of dementia, and excluding those who developed dementia shortly after baseline to reduce the risk of reverse causality
In this large community cohort study, we found a decline in SBP prior to dementia onset; participants with loss of longitudinal increase in SBP were over 20% more likely to develop dementia in subsequent years

Summary

Introduction

While hypertension is widely recognized as a risk factor for dementia, few observational studies and clinical trials fully accounted for the effect of age on blood pressure (BP) changes prior to dementia onset. More comprehensive studies are much needed to unravel how BP is associated with the development of dementia in older adults To address this knowledge gap, we conducted a large-scale longitudinal territory-wide population-based study and examined the risk of incident dementia across different SBP and DBP trajectories in late life, while taking into consideration the effects of hypertension, hypotension, BP variability, and other potential confounding factors including sociodemographics (age, sex, educational level, socioeconomic status), health problems (diabetes, hypercholesterolemia, obesity, heart diseases, sensory impairments, and depression) and lifestyle behaviours (physical exercise, intellectual and social activities, diet, smoking, and alcohol consumption), which themselves have already been shown to increase the risk of dementia, and excluding those who developed dementia shortly after baseline to reduce the risk of reverse causality. Characteristic Age, years Female No schooling received Low socioeconomic class Hypertension Diabetes Hypercholesterolemia Obesity Heart diseases Visual impairment Hearing impairment Poor balance Depression Physical exercise Intellectual activities Social activities Adequate fruit and vegetable intake Smoking Alcohol use Systolic blood pressure (SBP), mmHg Diastolic blood pressure (DBP), mmHg SBP ≥ 140 mmHg DBP ≥ 90 mmHg SBP ≥ 130 mmHg DBP ≥ 80 mmHg SBP < 100 mmHg DBP < 60 mmHg

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