Cardiovascular health, orthostatic hypotension, and cognitive aging

Abstract

Cardiovascular health (CVH) plays an important role in dementia development. Ideal CVH, defined by Life’s Simple 7 (LS7), has been associated with a lower risk of dementia in older adults. Orthostatic hypotension (OH) may be a novel cardiovascular risk factor that can affect dementia development. In this thesis, population-based cohort studies were conducted to investigate the role of LS7-defined CVH and OH in cognitive aging in people aged ≥60 years using data from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K).

Study I investigated LS7-defined CVH in relation to transitions between normal cognition, cognitive impairment, no dementia (CIND), and dementia. The study found that people with better CVH had a lower hazard of transitioning directly from normal cognition to CIND (HR = 0.76, 95% CI = 0.61-0.95) and dementia (HR = 0.42, 95% CI = 0.21-0.82) in people aged <78 years. In addition, people aged <78 years with better CVH had two to three more years of life living with normal cognition. However, CVH, defined by LS7, was not related to transitions between cognitive states in people aged ≥78 years.

Study II evaluated the associations between OH and dementia. Of the 2532 people who were initially free of dementia, 615 (24.3%) people had OH. People with OH had higher hazards of developing dementia (HR = 1.40, 95% CI = 1.10–1.76) and Alzheimer’s disease (HR = 1.39, 95% CI = 1.04–1.86). In addition, OH was related to a higher hazard of progression from CIND to dementia in people with CIND (HR = 1.54, 95% CI = 1.05–2.25) but not with incident CIND in those without CIND and dementia (HR = 1.15, 95% CI = 0.94–1.40).

Study III investigated the impact of OH on the development of CVDs and dementia in people initially free of CVDs as well as the impact of OH on dementia development in people with CVDs. The study found that in people who were initially free of CVDs, individuals who had OH at baseline had a higher hazard of developing CVDs (HR = 1.33, 95% CI = 1.12-1.59) but not dementia (HR = 1.22, 95% CI = 0.83-1.81) compared to those without OH. Among those with CVDs, persons with OH also had a higher hazard of dementia (HR = 1.54, 95% CI = 1.06-2.23) compared to those without OH.

Study IV assessed the associations of OH, in the presence or absence of frailty, with dementia and mortality. This study found that individuals who had OH at baseline had a higher hazard of dementia in the presence (HR = 2.73, 95% CI = 1.82-4.10) and absence (HR = 2.28, 95% CI = 1.47-3.54) of frailty than robust persons without OH. However, OH was only associated with a higher hazard of death without dementia when accompanied by frailty (HR = 1.56, 95% CI = 1.25-1.96).

Conclusions. Maintaining ideal CVH may protect against cognitive dysfunction and reduce years of life with cognitive dysfunction in younger old age. OH may be a potential modifiable risk factor for dementia, and the intermediate development of CVDs may help explain the association between OH and dementia.