Study: Low Blood Pressure Could be a Culprit in Dementia

Kenneth McLeod wrote . . . . . . . . .

Decline in brain function often occurs as people age. People often worry that declining brain function is an inevitable part of growing old and will lead to dementia, but it is not. Many people do not experience age-related cognitive decline.

Clinical studies that have followed older individuals over many years have consistently demonstrated that chronically low blood pressure increases the risk of age-related cognitive decline. For example, a study published in 2017 followed more than 24,000 people for up to 27 years. This study showed that low blood pressure is a significant predictor of cognitive decline and the probability of developing dementia. This was independent of age, gender, weight, cardiovascular, kidney or diabetic status.

Low blood pressure is associated with decreased blood flow to the brain when an individual is sitting or standing. Many researchers have come to believe that insufficient brain blood flow plays a critical role in the development of dementia, Alzheimer’s and perhaps even Parkinson’s disease. Some believe that it may even play the primary role.

Those of us who study the link between low blood pressure and cognitive performance need to determine what “too low” a blood pressure means in an individual person. This would allow health care providers to know when to intervene and correct a person’s low blood pressure. My team and I at the Clinical Science and Engineering Research Lab at Binghamton University are addressing this question.

What constitutes low blood pressure?

In our research, we are utilizing data obtained from a relatively new quantitative assessment tool cleared by the FDA for evaluating cognitive function in people over the age of 50 years, who have a high school degree or higher educational level.

This computer-based evaluation, which takes about 10 minutes for an individual to complete, provides clinicians and researchers with a reproducible assessment of cognitive function on a scale of 0-100. A score above 75 places the person in the expected cognitive function range for their age, while a score between 50 and 75 indicates an individual is in the below-normal range – and correspondingly, at increased risk of developing dementia. A score below 50 is indicative of an individual having many characteristics of dementia syndrome.

We have been comparing cognitive function scores in 50-95-year-olds to their resting blood pressures. Blood pressure is determined by measuring how much pressure is required to stop blood flow in the arteries of your arm. Resting blood pressure refers to your blood pressure after you have been sitting quietly for 10-15 minutes in a nonstressful environment. This is the blood pressure most older Americans experience most of the day, as older Americans are, on average, sedentary for over 9 hours.

Our previous work showed that of the two components of blood pressure – systolic and diastolic – diastolic blood pressure is the better predictor of cognitive performance. Diastolic blood pressures measures your blood pressure when your heart is relaxing and is the “lower number” of your blood pressure reading. We are focusing on this aspect of blood pressure.

Though our study is ongoing, two clear patterns are already developing in the data we have obtained from healthy subjects who have volunteered to be in the study – that is, people who have not been diagnosed with dementia or any other cognitive disorder.

First, low resting diastolic blood pressure is remarkably common. Over 85% of otherwise healthy 50-95-year-old subjects, in our study, have below normal resting diastolic blood pressures. This observation, by itself, would not necessarily be cause for concern. However, three-fourths of those we have studied so far, a total of 42 to date, with below normal blood pressure also test in the “below normal” cognitive function range.

Low blood pressure, also called hypotension, is usually defined as having a blood pressure low enough to cause dizziness, blurry vision or fainting. These symptoms typically occur with a diastolic pressure below 60 millimeters of mercury, or mmHg. Doctors tend not to be concerned about low blood pressure until diastolic pressure falls below this level.

Our data indicate that even individuals with diastolic blood pressures well above this 60mmHg threshold are unable to support normal cognitive function when upright. Indeed, at essentially any resting diastolic blood pressure below normal (80mmHg), the trend in the data indicates that cognitive performance in older adults is significantly reduced. Interestingly, these results are consistent with earlier reports of detrimental influences of low blood pressure on cognitive function even in young adults.

The surprising role of calf muscles

Low diastolic pressure can arise as a result of medication use, heart failure or other health complications. But, in most people, it is simply a matter of the heart not pumping out enough blood with each stroke; in other words, low cardiac output. And low cardiac output occurs when not enough blood is being returned to the heart from the lower body.

The soleus muscles, specialized muscles in the middle of your lower legs, are responsible for pumping blood back up to the heart. Over the last decade, our research team has demonstrated how the soleus muscles plays a critical role in maintaining normal blood pressure during sedentary activities.

An effective strategy for maintaining normal blood pressure, and brain blood flow, is to “re-train” your soleus muscles. These deep postural muscles are most active during activities such as sustained squatting or toe standing. You can rebuild these muscles by regularly undertaking such activities, though it requires hours a day of exercise.

Alternatively, “passive exercise” options exist which permit the “training-up” of your soleus muscles more conveniently. Both electrical and mechanical, soleus stimulation approaches have been shown to significantly increase venous return to the heart.

Preliminary clinical studies have also provided confirming evidence that raising resting diastolic blood pressure through daily soleus muscle stimulation, over a period of several months, can reverse the cognitive impairment associated with aging.

No treatments currently exist for dementia, and no potential treatment seems to be on the horizon, and so the health care community has become much more focused on slowing, or reversing, cognitive aging to prevent progression to dementia.

If interventions to eliminate chronically low diastolic blood pressure are simple and direct, we may well have the opportunity to largely eliminate much of the scourge of dementia from modern life.

Source: The Conversation


Using Walking Patterns to Diagnose Specific Dementia Type

For the first time, scientists at Newcastle University have shown that people with Alzheimer’s disease or Lewy body dementia have unique walking patterns that signal subtle differences between the two conditions.

The research, published today in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, shows that people with Lewy body dementia change their walking steps more – varying step time and length – and are asymmetric when they move, in comparison to those with Alzheimer’s disease.

It is a first significant step towards establishing gait as a clinical biomarker for various subtypes of the disease and could lead to improved treatment plans for patients.

Useful diagnostic tool

Dr Ríona McArdle, Post-Doctoral Researcher at Newcastle University’s Faculty of Medical Sciences, led the Alzheimer’s Society-funded research.

She said: “The way we walk can reflect changes in thinking and memory that highlight problems in our brain, such as dementia.

“Correctly identifying what type of dementia someone has is important for clinicians and researchers as it allows patients to be given the most appropriate treatment for their needs as soon as possible.

“The results from this study are exciting as they suggest that walking could be a useful tool to add to the diagnostic toolbox for dementia.

“It is a key development as a more accurate diagnosis means that we know that people are getting the right treatment, care and management for the dementia they have.”

Current diagnosis of the two types of dementia is made through identifying different symptoms and, when required, a brain scan.

For the study, researchers analysed the walk of 110 people, including 29 older adults whose cognition was intact, 36 with Alzheimer’s disease and 45 with Lewy body dementia.

The participants took part in a simple walking test at the Gait Lab of the Clinical Ageing Research Unit, an NIHR-funded research initiative jointly run by Newcastle Hospitals NHS Foundation Trust and Newcastle University.

Participants moved along a walkway – a mat with thousands of sensors inside – which captured their footsteps as they walked across it at their normal speed and this revealed their walking patterns.

People with Lewy body dementia had a unique walking pattern in that they changed how long it took to take a step or the length of their steps more frequently than someone with Alzheimer’s disease, whose walking patterns rarely changed.

When a person has Lewy body dementia, their steps are more irregular and this is associated with increased falls risk. Their walking is more asymmetric in step time and stride length, meaning their left and right footsteps look different to each other.

Scientists found that analysing both step length variability and step time asymmetry could accurately identify 60% of all dementia subtypes – which has never been shown before.

Further work will aim to identify how these characteristics enhance current diagnostic procedures, and assess their feasibility as a screening method. It is hoped that this tool will be available on the NHS within five years.

Pioneering study

Dr James Pickett, Head of Research at Alzheimer’s Society, said: “In this well conducted study we can see for the first time that the way we walk may provide clues which could help us distinguish between Alzheimer’s disease and Lewy body dementia.

“This research – funded by the Alzheimer’s Society – is pioneering for dementia. It shows promise in helping to establish a novel approach to accurately diagnose different types of dementia.

“We know that research will beat dementia, and provide invaluable support for the 850,000 people living with the condition in the UK today. It’s now vital that we continue to support promising research of this kind.

“We look forward to seeing larger, longer studies to validate this approach and shed light on the relationship between a person’s gait and dementia diagnosis.”

Dementia describes different brain disorders that triggers loss of brain function and these conditions are usually progressive and eventually severe.

It is estimated by the Alzheimer’s Society that people living with dementia in the UK will rise to more than one million by 2025.

Source: Newcastle University

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Brain Changes May Help Track Dementia, Even Before Diagnosis

Even before a dementia diagnosis, people with mild cognitive impairment may have different changes in the brain depending on what type of dementia they have, according to a study published in the online issue of Neurology®, the medical journal of the American Academy of Neurology.

“These differences may reflect underlying changes in the brain that could be used to track early changes in people who are going to develop either Alzheimer’s disease or dementia due to cerebrovascular disease,” said study author Juan “Helen” Zhou, PhD, of Duke-NUS Medical School in Singapore and a member of the American Academy of Neurology.

The study involved people recruited from Samsung Medical Center in South Korea: 30 people with mild cognitive impairment including memory problems, which is often considered an early stage of Alzheimer’s disease, and 55 people with mild cognitive impairment with damage to small blood vessels in the brain, which is an early sign of vascular dementia, or dementia due to cerebrovascular disease.

The participants had positron emission tomography (PET) scans at the start of the study to see if they had amyloid-beta plaques in the brain that are associated with Alzheimer’s disease, and structural MRI scans to see if they had the signs of cerebrovascular disease associated with vascular dementia. The functional MRI scans were used to measure how brain regions are functionally connected. These scans were repeated every year for up to four years.

The functional MRI scans were looking at functional networks in the brain—the executive control network, which is engaged during activities such as use of working memory and switching between tasks; and the default mode network, which has been linked to memory retrieval.

The researchers found that the interactions in the default network declined more steeply over time in the people who had amyloid-beta plaques in the brain confirming Alzheimer’s disease than in people in early stages of vascular dementia and without amyloid-beta plaques in the brain. Specifically, the rate of annual decline in the default mode network connections was on average 13.6 times faster in the people who had amyloid-beta plaques in the brain confirming Alzheimer’s disease than in people in the early stages of vascular dementia and without amyloid-beta plaques.

Researchers also found that the rate of annual increase in interactions in the executive control network was on average three times faster in people in the early stages of vascular dementia and without amyloid-beta plaques than in people in the early stages of Alzheimer’s disease.

“More studies are needed with larger numbers of participants and longer follow-up periods, but these results suggest that these changes in brain network connections could potentially be used to track early changes in Alzheimer’s disease and cerebrovascular disease,” said study author Sang Won Seo, MD, of Samsung Medical Center in South Korea.

Limitations of the study were the small number of participants and the relatively short time for follow-up.

Source: American Academy of Neurology

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Advanced MRI Brain Scan May Help Predict Stroke-related Dementia

An advanced Magnetic Resonance Imaging (MRI) brain scan analysis in patients with stroke-related, small vessel disease helped predict problems with thinking, memory and even dementia, according to new research published in Stroke, a journal of the American Stroke Association, a division of the American Heart Association.

When a stroke or other disease damages tiny blood vessels in the brain, the condition is known as small vessel disease. This condition is the most common cause of thinking problems (planning, organizing information and processing speed) and can even lead to dementia. Although early treatment could help patients at risk, no effective test is available to identify them.

This study evaluated the accuracy of a new MRI analysis technique using diffusion tensor imaging (DTI), in predicting thinking problems and dementia related to small vessel disease. A single scan measured the brain in fine detail to reveal damaged areas. By comparing these images to a healthy person’s, researchers were able to classify the brain into areas of healthy versus damaged tissue.

Results showed that participants with the most brain damage were much more likely to develop thinking problems. The analysis also helped predict three-fourths of the dementia cases that occurred during the study.

“We have developed a useful tool for monitoring patients at risk of developing dementia and could target those who need early treatment,” said senior author Rebecca A. Charlton, Ph.D., department of psychology at Goldsmiths, University of London, in the United Kingdom.

The study included 99 patients with small vessel disease caused by ischemic stroke, a type of stroke that blocks the blood vessels deep within the brain. Slightly more than one-third were female, average age 68, and most were Caucasian. All participants were enrolled in the St George’s Cognition and Neuroimaging in Stroke (SCANS) study from 2007 to 2015 in London.

Participants received the MRI scans annually for three years and thinking tests annually for five years. Eighteen participants developed dementia during the study, with an average time to onset of approximately three years and four months.

This advanced MRI analysis offers a highly accurate and sensitive marker of small vessel disease severity in a single measure that can be used to detect who will and will not go on the develop dementia in a five-year period, noted Charlton.

The healthy brain scans used for comparison were from one individual and may not represent the true range of all healthy brains. In addition, the study’s relatively small number of participants all had small vessel disease resulting from one type of stroke, so the results may not apply to people with different forms of the disease.

Source: American Heart Association

Dodge Dementia With Healthy Lifestyle

Dodge Dementia With Healthy Lifestyle

Amy Norton wrote . . . . . . . . .

Seniors, here’s a recipe for preventing dementia: eat well, exercise and don’t smoke.

The only catch, according to a new study? If you carry genes that leave you vulnerable to the memory-robbing disease, lifestyle might not be enough.

In the study, researchers found that of over 6,300 adults aged 55 and older, those with healthy habits had a lower risk of being diagnosed with dementia over the next 15 years. That was true, at least, for people at low or intermediate risk of dementia because of their genes.

Among people who carried high-risk genes, there was no evidence that lifestyle swayed the odds of developing dementia.

The findings, published Aug. 26 in the journal Nature Medicine, support a number of past studies suggesting that heart-healthy habits may also protect the brain.

But they are at odds with some past research, too: Other studies have suggested that lifestyle choices do, in fact, make a difference for people at high genetic risk for dementia.

The reasons for the differing findings are unclear. But the age of the study participants could be a factor, according to lead researcher Dr. Silvan Licher, of Erasmus MC-University Medical Center, in Rotterdam, the Netherlands.

People in his study were about 69 years old, on average, when their lifestyle habits were measured. But it might be healthy habits earlier in life — middle-age or sooner — that are critical for countering a high genetic risk for dementia.

So, the point is not to discourage anyone from following a healthy lifestyle, Licher stressed.

“These results should not alter the message about the importance of a healthy lifestyle to lower the risk of dementia,” he said.

If anything, he added, the findings offer “an extra incentive” to adopt healthy habits now instead of later. The benefits, Licher noted, are numerous — including lower risks of heart disease and stroke.

For the study, the researchers assigned participants into groups based on the genes they carried. The investigators used two different approaches to do that. In one, they focused on the APOE gene; certain variants of that gene are linked to a relatively higher risk of Alzheimer’s disease. In the second, they considered an array of genes that have been tied to dementia risk — assigning each participant a “polygenic” score.

Licher’s team also scored the participants based on certain lifestyle and health factors: exercise habits; diet and alcohol intake; smoking; and whether they had diabetes, depression or were socially isolated.

Over the next 15 years, people with a “favorable” lifestyle score were less likely to develop dementia — if they were not at high genetic risk, the findings showed.

The difference was clear, for example, among people with low-risk APOE scores: Those with a favorable lifestyle had a much lower rate of dementia — less than 13%, versus 32% of those with an unhealthy lifestyle.

A similar pattern turned up among people at intermediate APOE risk, which the majority of study participants were.

The picture was different for people at high APOE risk. About 18% of those with a healthy lifestyle developed dementia, versus 19.5% of those with unhealthy habits.

It’s hard to know the reasons for that finding — or why it conflicts with some past studies, according to Rebecca Edelmayer, director of scientific engagement at the Alzheimer’s Association.

But she agreed that the message about lifestyle remains unchanged. “We have a body of evidence suggesting that adopting a healthy lifestyle is not only good for cardiovascular health, but for brain health, too,” Edelmayer said.

Ultimately, she added, it will take clinical trials to get more solid answers.

The Alzheimer’s Association is currently funding a trial, called U.S. Pointer, which is testing a combination of measures — including exercise, mental stimulation, and better control of blood pressure and diabetes. It’s looking at whether those steps can help prevent mental decline in older adults believed to be at increased risk.

It would be much harder to run a similar trial in middle-aged adults — since it would take many years to see any effects, Edelmayer noted. But in general, she said, it’s thought that people stand to benefit the most by making healthy changes as early as possible.

“It’s never too early to start,” she said.

Source: HealthDay

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