Study: High Blood Pressure Threatens Aging Brain

Maureen Salamon wrote . . . . . . . . . .

Here’s yet another reason to get your blood pressure under control: High blood pressure later in life may contribute to blood vessel blockages and tangles linked to Alzheimer’s disease, new research suggests.

Tracking nearly 1,300 older people until they died, scientists found markedly higher risks of one or more brain lesions among those with high systolic blood pressure readings.

These lesions were dominated by so-called “infarcts” — areas of dead tissue prompted by blood supply blockages that can trigger strokes.

Normal blood pressure is defined as 120/80 mm/Hg or lower. The top number is known as systolic blood pressure (pressure in vessels during heartbeats), while the lower number is diastolic blood pressure (pressure between beats).

Late last year, the American College of Cardiology and American Heart Association changed blood pressure recommendations, defining high blood pressure as 130/80 mm/Hg or higher.

“We’ve known for many decades that higher blood pressure, especially younger in life, is related to strokes. But we know a lot less regarding cerebrovascular disease and wanted to examine the question of blood pressure later in life,” said study author Dr. Zoe Arvanitakis. She’s medical director of the Rush Memory Clinic in Chicago.

“I think this information is of great value to researchers who study brain changes in aging,” she added, “and certainly points to the need for a lot more research to be done.”

Arvanitakis and her team followed nearly 1,300 people until their death, which occurred at an average age of nearly 89. Two-thirds of the participants, who were mostly women, had a history of high blood pressure, and 87 percent took blood pressure medication.

Using autopsy results after participants’ deaths, the researchers learned that 48 percent had one or more brain infarct lesions. The risk of lesions was higher in those with higher average systolic blood pressure readings over the years.

For example, for someone with an average systolic blood pressure of 147 mm/Hg compared to 134 mm/Hg, the odds of brain lesions increased 46 percent. A smaller but still notable increased risk of brain lesions was found in those with elevated diastolic blood pressure as well.

Looking for signs of Alzheimer’s disease in autopsied brains, the researchers also saw an association between higher systolic blood pressure in the years before death and higher amounts of tangles — knots of brain cells signifying the presence of the condition.

However, amyloid plaques, which also characterize an Alzheimer’s-affected brain, weren’t linked to blood pressure in the research. Arvanitakis said more studies are needed.

Dr. Ajay Misra is chairman of neurosciences at NYU Winthrop Hospital in Mineola, N.Y. He described the study as “very important” and said it should prompt crucial dialogue about how to best manage blood pressure in older adults.

“A lot of good information came out, but there are more questions than answers,” said Misra, who wasn’t involved in the new research. “This study was done to provoke that sort of questioning.”

Misra noted the study found that rapidly decreasing blood pressure in older adults actually increased stroke risks. A potential reason for that, he said, is that arteries become less elastic as we age, so slightly higher blood pressure is necessary to keep blood flowing adequately.

“This acts as a reminder that you cannot just go and publish that one set of blood pressure guidelines is good for all,” he added. “I think it will either be age-specific about how blood pressure should be maintained, or there should be some disease- or circumstance-specific guidelines.”

The study was published online in the journal Neurology.

Source: HealthDay


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Biomarker for Salt Sensitivity of Blood Pressure Discovered

For the first time researchers have identified a genetic marker (GNAI2) that is associated with the risk of salt sensitivity in blood pressure (BP) regardless of age or gender.

It is hoped that with this discovery a simple test to identify salt sensitivity of BP during a clinical visit can be developed.

High blood pressure (hypertension) impacts nearly one of every two adults in the U.S. and is the leading global non-communicable cause of death. It is projected to be the primary global cause of death and disability by 2020. Salt sensitivity in blood pressure is a major risk factor for hypertension and increased cardiovascular risk and is highly relevant given that 99 percent of U.S. adults exceed the recommended daily intake for salt.

“Our data highlights a potential genetic method to screen for the salt sensitivity of blood pressure that may identify patients who exhibit the salt sensitivity of blood pressure. Possessing this specific marker makes you three times more likely to be salt sensitive than people who don’t have the marker,” explained corresponding author Richard Wainford, PhD, associate professor of Pharmacology & Experimental Therapeutics at Boston University School of Medicine (BUSM).

The researchers looked at two groups of patients. The first group had no change in blood pressure in response to high dietary salt intake (meaning they were salt resistant). The second group of patients had an increase in blood pressure in response to high dietary salt intake (salt sensitive). Both groups were then screened for genetic variation in the GNAI2 gene. Those patients with the gene variation were more likely to be salt sensitive.

“Developing a simple diagnostic biomarker of individual salt-sensitivity of BP would aid in identifying individuals at risk for developing salt sensitivity related complications (hypertension, cardiac, renal and cerebral diseases), and in risk stratification and treatment decisions in individuals with established salt-sensitive conditions.”

The findings appear in the journal Physiological Genomics.

Source: Science Daily


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Hypertension May Cause Dementia

A new study in Cardiovascular Research, published by Oxford University Press, indicates that patients with high blood pressure are at a higher risk of developing dementia. This research also shows (for the first time) that an MRI can be used to detect very early signatures of neurological damage in people with high blood pressure, before any symptoms of dementia occur.

High blood pressure is a chronic condition that causes progressive organ damage. It is well known that the vast majority of cases of Alzheimer’s disease and related dementia are not due to genetic predisposition but rather to chronic exposure to vascular risk factors.

The clinical approach to treatment of dementia patients usually starts only after symptoms are clearly evident. However, it has becoming increasingly clear that when signs of brain damage are manifest, it may be too late to reverse the neurodegenerative process. Physicians still lack procedures for assessing progression markers that could reveal pre-symptomatic alterations and identify patients at risk of developing dementia.

Researchers screened subjects admitted at the Regional Excellence Hypertension Center of the Italian Society of Hypertension in the Department of Angiocardioneurology and Translational Medicine of the I.R.C.C.S, Neuromed, in Italy. Researchers recruited people aged 40 to 65, compliant to give written informed consent and with the possibility to perform a dedicated 3 Tesla MRI scan.

This work was conducted on patients with no sign of structural damage and no diagnosis of dementia. All patients underwent clinical examination to determine their hypertensive status and the related target organ damage. Additionally, patients were subjected to an MRI scan to identify microstructural damage.

To gain insights in the neurocognitive profile of patients a specific group of tests was administered. As primary outcome of the study the researchers aimed at finding any specific signature of brain changes in white matter microstructure of hypertensive patients, associated with an impairment of the related cognitive functions.

The result indicated that hypertensive patients showed significant alterations in three specific white matter fiber-tracts. Hypertensive patients also scored significantly worse in the cognitive domains ascribable to brain regions connected through those fiber-tracts, showing decreased performances in executive functions, processing speed, memory and related learning tasks.

Overall, white matter fiber-tracking on MRIs showed an early signature of damage in hypertensive patients when otherwise undetectable by conventional neuroimaging. As these changes can be detected before patients show symptoms, these patients could be targeted with medication earlier to prevent further deterioration in brain function. These findings are also widely applicable to other forms of neurovascular disease, where early intervention could be of marked therapeutic benefit.

“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. In both cases, it is often too late to stop the pathological process” said Giuseppe Lembo, the coordinator of this study.

“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. Of course, further studies will be necessary, but we think that the use of tractography will lead to the early identification of people at risk of dementia, allowing timely therapeutic interventions.”

Source: EurekAlert!


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Drug Therapy Fails to Control Blood Pressure During Exercise

People with high but under control blood pressure saw a jump in their levels during exercise, an increase that mirrored the spikes seen under similar conditions among people with untreated hypertension, according to a new British study.

The findings open up the possibility of tailoring blood pressure treatment to a patient’s activity level.

But the study’s senior author emphasized that routine exercise continues to be one of the best ways to help lower blood pressure in the long run, since regular physical activity strengthens the heart and allows it to pump more blood with less effort.

“We don’t want to put people off exercising because it’s been proven that training to be fitter does help control blood pressure, which in return reduces your risk of having a heart attack and stroke,” said Emma Hart, an associate professor at the University of Bristol’s School of Physiology, Pharmacology and Neuroscience.

She’s the senior author of the study published in the American Heart Association journal Hypertension.

Researchers measured the impact of sudden exercise on four small groups of people, 59 in all. Three of those groups had high blood pressure: one had the condition under control through treatment, primarily medication; another group received treatment but did not have it controlled; and the third group did not treat their high blood pressure at all. The fourth group had normal blood pressure.

In the study led by Benjamin Chant, a doctoral student at the University of Bristol, participants in all four groups took exercise tests on stationary bicycles. They had their blood pressure measured every 90 seconds until they reached a point where they couldn’t exercise any further.

Blood pressure generally rises for everyone during exercise, but only to reasonable levels in people who are healthy.

But blood pressure rose excessively among the study group who had their blood pressure under control. Similar rises occurred among patients whose condition was either uncontrolled or untreated.

The exaggerated increase started when participants had only reached a moderate level of exercise — around 50 percent of their peak point.

“We’re now starting to think that it may be more important to aim for controlling blood pressure during physical activity, even just day-to-day physical activity, rather just at rest,” Hart said. “Because if you’re getting these repeated rises in excessive blood pressure, then that’s probably not good for your cardiovascular system.”

Researchers believe part of the reason for that increase is a chemical byproduct released by muscles during exercise that tells the brain to increase blood pressure. This process, called the metaboreflex, is hyperactive in people who have high blood pressure. The new findings suggest the reflex also is fairly immune to medications that are normally prescribed to treat high blood pressure.

Peter Raven, a retired physiology and anatomy professor with the University of North Texas Health Science Center who was not involved in the study, said the report’s findings suggest that doctors shouldn’t base their efforts to control blood pressure on measurements taken when people are at rest.

“They really should be tested, within a clinical setting, during exercise. It could be at the moderate level, but I would suggest they be taken at the max, so that you could identify whether the drug therapy they’re using is the one that will maintain their blood pressure even while they’re exercising,” said Raven, who wrote an editorial that accompanied the study.

Hart again appealed to people to continue exercising — but after consulting with their doctor first. She noted that her study was conducted on generally inactive people given a “one-off bout of exercise.”

“I live in Bristol, which is very hilly. If someone who is very sedentary suddenly needs to walk up a hill, that might not be good,” she said. “But if you are more trained — say you’re repeatedly climbing up that hill every week — then that probably will help reduce your risk of having a cardiovascular event.”

Hart said next steps will involve taking a look at more fit people and the impact that fitness level has on blood pressure during exercise.

Source: HealthDay


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Risk of Dementia is Increased in 50-year-olds with Blood Pressure Below the Current Threshold for Hypertension

New findings from the long-running Whitehall II study of over 10,000 civil servants has found 50-year-olds who had blood pressure that was higher than normal but still below the threshold commonly used when deciding to treat the condition, were at increased risk of developing dementia in later life.

This increased risk was seen even when the study participants did not have other heart or blood vessel-related problems, according to the research, which is published in the European Heart Journal [1] today.

Although there have been previous studies that have linked raised blood pressure in midlife to an increased risk of dementia in later life, the term ‘midlife’ has been poorly defined and ranged from 35 to 68 years.

The first author of the paper, Dr Jessica Abell, post-doctoral research fellow at the French National Institute of Health and Medical Research in Paris (INSERM) and a research associate in dementia and epidemiology at University College London (UCL), UK, said: “Previous research has not been able to test the link between raised blood pressure and dementia directly by examining the timing in sufficient detail. 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’.”

Participants in the Whitehall II study, who were aged between 35-55 in 1985, had their blood pressure measured in 1985, 1991, 1997 and 2003. Other medical information was also taken, such as age, sex, lifestyle behaviours (such as smoking and alcohol intake), and socio-demographic factors.

Among the 8,639 people analysed for this study, 32.5% of whom were women, 385 developed dementia by 2017. Those who had a systolic blood pressure of 130 mmHg or more at the age of 50 had a 45% greater risk of developing dementia than those with a lower systolic blood pressure at the same age. This association was not seen at the ages of 60 and 70, and diastolic blood pressure was not linked to dementia [2].

The link between high blood pressure and dementia was also seen in people who had no heart or blood vessel-related conditions (cardiovascular disease) during the follow-up period; they had an increased risk of 47% compared to people with systolic blood pressure lower than 130 mmHg at age 50.

Guidelines from NICE (National Institute for Health and Care Excellence) in the UK and the European Society of Cardiology both give a threshold of 140/90 mmHg for hypertension, although 2017 guidelines from the American Heart Association, the American College of Cardiology and nine other health organisations lowered the threshold to 130/80 mmHg for all adults. Ideal blood pressure is considered to be between 90/60mmHg and 120/80mmHg.

Professor Archana Singh-Manoux, research professor at INSERM and honorary professor at UCL, who led the research, said: “Our work confirms the detrimental effects of midlife hypertension for risk of dementia, as suggested by previous research. It also suggests that at age 50, the risk of dementia may be increased in people who have raised levels of systolic blood pressure below the threshold commonly used to treat hypertension.

“Our analysis suggests that the importance of mid-life hypertension on brain health is due to the duration of exposure. 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 average age at which the study participants developed dementia was 75.

Possible reasons for the link between raised blood pressure and dementia include the fact that high blood pressure is linked to silent or mini strokes (where symptoms often are not noticeable), damage to the white matter in the brain, which contains many of the brain’s nerve fibres, and restricted blood supply to the brain. This damage may underlie the resulting decline in the brain’s processes.

Dr Abell said: “It is important to emphasise 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. 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.”

Limitations of the study include the fact that diagnosis of dementia was made by linking to electronic medical records that might miss milder cases of dementia; the researchers were not able to examine whether the association of hypertension was stronger with Alzheimer’s disease or vascular dementia because of the small numbers in the study affected by dementia, and this requires further research; and the researchers do not know whether effective management of high blood pressure in people in mid-life might weaken the risk of later dementia.

“One of the strengths of this study was having repeat blood pressure measurements on the same people, which allowed us to examine their blood pressure status over an 18-year period. This is rare, since previous research has often used a single measure of hypertension,” concluded Professor Singh-Manoux.

Source: European Society of Cardiology