Blood pressure in midlife that was higher than normal — but below the threshold used to treat hypertension in some countries — was linked to increased risk of developing dementia later in life, an analysis of the long-running Whitehall II study found.
Men and women who had a systolic blood pressure ≥130 mm Hg at age 50 had a 45% greater risk of developing dementia than people with a lower systolic blood pressure at the same age, reported Archana Singh-Manoux, PhD, of the French National Institute of Health and Medical Research (INSERM) in Paris, and colleagues in European Heart Journal.
This association was not seen at ages 60 or 70.
“Our analysis suggests that the importance of midlife hypertension on brain health is due to the duration of exposure,” Singh-Manoux said in a statement. “So we see an increased risk for people with raised blood pressure at age 50, but not 60 or 70, because those with hypertension at age 50 are likely to be exposed to this risk for longer.”
The American Heart Association, the American College of Cardiology and other health organizations recently lowered the stage 1 hypertension threshold to 130/80 mm Hg for adults, but guidelines from NICE (National Institute for Health and Care Excellence) in the U.K. and the European Society of Cardiology have thresholds of 140/90 mm Hg.
“This is an important study in that it further describes the dangers of borderline hypertension, particularly during middle life,” commented John Bisognano, MD, of the University of Rochester Medical Center in Rochester, New York, who was not involved with the study.
“We’ve known for over 30 years that people with even mild hypertension have increased cardiovascular risk factors and, presumably, poorer outcomes,” he told MedPage Today. “But general public health guidelines have been slow to embrace the importance of this condition, as there is a scarcity of studies investigating the effect of drug therapy in this group.”
Whitehall II is an ongoing study of aging at the University College London. In this analysis, researchers assessed 8,639 people aged 35 to 55 in 1985 who had their blood pressure measured then, and again in 1991, 1997, and 2003. By the study’s end in March 2017, 385 individuals had developed dementia; their average age was 75.2 at dementia diagnosis.
Systolic pressure starting from 130 mm Hg at age 50, but not at age 60 or 70, was associated with increased risk of dementia (HR 1.45; 95% CI 1.18-1.78). This association continued even after adjusting for diabetes, coronary heart disease, stroke, atrial fibrillation, heart failure, and cardiovascular medication (HR 1.38, 95% CI 1.11-1.70). Diastolic blood pressure was not associated with dementia.
Even among people who did not have cardiovascular disease, systolic blood pressure ≥130 mm Hg at age 50 was associated with greater risk of dementia (HR 1.47, 95% CI 1.15-1.87), suggesting that clinical cardiovascular disease did not fully account for the association and subclinical vascular brain lesions may be involved.
“It makes sense that having hypertension for a longer period of time could increase the risk for dementia,” Sandra Taler, MD, of the Mayo Clinic in Rochester, Minnesota, who was not involved in the study, told MedPage Today. “This would certainly create an incentive in middle-aged individuals to note their hypertension and bring blood pressure down to normal by lifestyle changes, with or without medication.”
“The take-home message is that blood pressure elevations in middle age are important to follow and to discuss with patients, as things only get worse in most people and blood pressure moves up as people age,” added Bisognano.
“Importantly, when patients are in their 30s and 40s and the first uptick in blood pressure is seen, it’s no time to reassure them that everything is okay, although they may be seeking reassurance that they’re not about to start a trip down the moving sidewalk to full-blown hypertension,” he said.
“Rather than reassuring them and kicking the can down the road, it’s time to focus intensively on their lifestyle and activity level at an age when they can actually make a difference and avoid a trajectory that will give them sustained elevations of their blood pressure as they hit 50 and more risk of dementia as they get older.”
This study is observational, population-level research and findings do not translate directly into implications for individual patients, the researchers noted. Limitations include the fact that mild dementia diagnoses might not have been captured in electronic medical records. Due to the small number of dementia patients, the researchers also could not determine whether hypertension associations were stronger with vascular dementia or Alzheimer’s disease.
The Whitehall II study is supported by the US National Institutes of Health (NIH), the UK 10 Medical Research Council (MRC), and the British Heart Foundation (BHF); Horizon2020; EC Horizon2020; NordForsk and the Academy of Finland.
The researchers reported no conflicts of interest.