Whitehall II: Systolic BP Above 130 mm Hg at Age 50 Heightens Risk of Dementia
The findings from the study of British civil servants followed for decades support the most recent ACC/AHA hypertension guidelines.
Middle-age adults with systolic blood pressures in a range once considered prehypertensive could have as much as a 45% increased risk of developing dementia, regardless of whether they have concomitant cardiovascular disease, according to new data from the ongoing Whitehall II study.
“Our results show high blood pressure at age 50 increases risk of dementia later in life. We also show that risk begins below the current threshold of systolic blood pressure used to begin treatment,” Archana Singh-Manoux, PhD (French National Institute of Health and Medical Research, Paris, France), the study’s senior author, said in an email.
The findings support the lowering of the treatment goal for systolic BP to less than 130 mm Hg, as set forth late last year in new comprehensive hypertension guidelines from the American Heart Association (AHA), American College of Cardiology (ACC), and nine other medical societies. Of note, however, updated European guidelines, highlights of which were released last week, have elected to use less aggressive treatment targets than those in the US document and have maintained conventional hypertension classifications, with grade 1 hypertension starting at an office pressure of 140/90 mm Hg.
Singh-Manoux and colleagues say that although previous studies have suggested that hypertension in midlife contributes to dementia, the definition of what constitutes ‘midlife’ or ‘middle age’ has been unclear. In their study, they examined the link between high BP at specific ages and later development of dementia and found that only those with high blood pressure at age 50, but not at age 60 or 70, were at increased risk of dementia. The study found no link between increased diastolic BP (≥ 90 mm Hg) at any age and risk of dementia.
According to Singh-Manoux, the increased risk is believed to be related to longer exposure to the detrimental effects of hypertension.
“Living with high blood pressure for longer means that the blood vessels in the brain are subject to damage over a longer period,” she said.
The study was led by Singh-Manoux’s colleague Jessica G. Abell, MD (French National Institute of Health and Medical Research), and published online June 13, 2018, ahead of print in the European Heart Journal.
Subclinical Vascular Brain Lesions Implicated
In the ongoing Whitehall II study of 6,895 male and 3,413 female British civil servants who were ages 35 to 55 years when the study began, BP was measured in 1985, 1991, 1997, and 2003. The study collects a range of information on the participants, including lifestyle behaviors like smoking and alcohol use, as well as sociodemographic factors.
From 1985 to 2017, 385 individuals were diagnosed with dementia at a mean age of 75 years. After adjustment for age, sex, education, ethnicity, marital status, and occupational position, those who had a systolic BP of at least 130 mm Hg at age 50 had a 45% greater risk of developing dementia compared with those with a lower systolic blood pressure at the same age (HR 1.45; 95% CI 1.18-1.79). In contrast, patients with a systolic BP of at least 130 mm Hg at age 60 or 70 had no significant elevations in risk (HR 1.05; 95% CI 0.84-1.32 and HR 1.07; 95% CI 0.80-1.42, respectively).
Furthermore, in analyses looking at use of antihypertensive medication or systolic BP ≥ 130 mm Hg at age 50, only age was associated with incidence of dementia (HR 1.37; 95% CI 1.11, 1.70). Among those who were age 60, use of antihypertensives was associated with increased risk of dementia (HR 1.62; 95% CI 1.21-2.18), but systolic BP ≥ 130 mm Hg was not. For those age 70, neither use of antihypertensive medication nor systolic BP ≥ 130 mm Hg was associated with dementia.
Although patients with hypertension at age 50 were more likely to have CVD, even those free of CVD had an increased risk of dementia with BP ≥ 130 mm Hg at age 50 (HR 1.47; 95% CI 1.15-1.87).
“These results suggest that subclinical or ‘silent’ vascular brain lesions (ie, infarcts, microbleeds, white matter changes), which are common in those with hypertension, may be involved in increased dementia risk in those with high blood pressure who do not have clinical CVD,” Abell and colleagues write. “Thus, cerebral small vessel disease is likely to be an important mechanism underlying the association of high blood pressure and cognitive dysfunction.”
Abell JG, Kivimäki M, Dugravot A, et al. Association between systolic blood pressure and dementia in the Whitehall II cohort study: role of age, duration, and threshold used to define hypertension. Eur Heart J. 2018;Epub ahead of print.
- The Whitehall II study is supported by grants from the US National Institutes of Health, the UK Medical Research Council, the British Heart Foundation, Horizon2020, EC Horizon2020, NordForsk, and the Academy of Finland.
- Abell and Singh-Manoux report no relevant conflicts of interest.