Studies: Higher blood pressure increases risk for dementia

By Allen Cone  |  Updated June 13, 2018 at 11:30 AM
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June 13 (UPI) -- Two studies released this week link higher blood pressure in middle-aged people to a greater risk of neurological damage, including dementia.

People with higher blood pressure, including those below guidelines for hypertension, have an increased risk for dementia, according to researchers in Europe. Researchers in Italy were able to show neurological damage due to higher blood pressure in MRI scans, and may be the first to do so.

Previous research has linked high blood pressure as a chronic condition that causes progressive organ damage. And other studies have found most Alzheimer's disease and related dementia aren't linked to genetics, but instead chronic exposure to vascular risk factors.

But dementia diagnoses usually occur only after symptoms are quite evident -- too late to reverse the neurodegenerative process.

"The problem is that neurological alterations related to hypertension are usually diagnosed only when the cognitive deficit becomes evident, or when traditional magnetic resonance shows clear signs of brain damage," Dr. Giuseppe Lembo, a researcher at Sapienza University of Rome and IRCCS Neuromed in Italy, said in a press release. "In both cases, it is often too late to stop the pathological process."

In an analysis of data from the Whitehall II study, published Tuesday in the European Heart Journal, researchers looked at data from 8,639 civil servants collected in 1985, 1991, 1997 and 2003.

The researchers found that 50-year-olds who had a systolic blood pressure of 130 mmHg or more had a 45 percent greater risk of developing dementia than those with a lower blood pressure at the same age. This is despite no other heart or blood vessel-related problems, they say. The association between high blood pressure and dementia didn't appear in people between 60 and 70.

"Previous research has not been able to test the link between raised blood pressure and dementia directly by examining the timing in sufficient detail," Dr. Jessica Abell, a post-doctoral research fellow at the French National Institute of Health and Medical Research in Paris and a research associate in dementia and epidemiology at University College London, said in a press release. "In our paper we were able to examine the association at age 50, 60 and 70, and we found different patterns of association. This will have important implications for policy guidelines, which currently only use the generic term 'midlife.'"

Lembo led a separate study of MRI scans from people aged 40 to 65 admitted at the Regional Excellence Hypertension Center of the Italian Society of Hypertension. The findings were published Monday in the journal Cardiovascular Research.

Researchers wanted to find any specific signature of brain changes in white matter microstructure of hypertensive patients, which is associated with an impairment of the related cognitive functions.

They found hypertensive patients showed significant alterations in three specific white matter fiber-tracts. In addition, hypertensive patients also performed significantly worse in cognitive tests, including domains processing speed, memory and related learning tasks.

Overall, MRI's detected white matter fiber-tracking as an early sign of damage in hypertensive patients when otherwise undetectable by conventional neuroimaging.

"We have been able to see that, in the hypertensive subjects, there was a deterioration of white matter fibers connecting brain areas typically involved in attention, emotions and memory," said Lorenzo Carnevale, IT engineer and first author of the study. "An important aspect to consider is that all the patients studied did not show clinical signs of dementia and, in conventional neuroimaging, they showed no signs of cerebral damage."

Researchers in both studies say more work is necessary -- especially in determining an ideal level for blood pressure that does not increase risk for dementia -- but that maintaining some level of healthy blood pressure is a good idea.

"It is important to emphasize that this is observational, population-level research and so these findings do not translate directly into implications for individual patients. Furthermore, there is considerable discussion on the optimal threshold for the diagnosis of hypertension," Abell said.

"There is plenty of evidence to suggest that maintaining a healthy blood pressure in middle age is important for both your heart and your brain later in life. Anyone who is concerned about their blood pressure levels should consult their GP."

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