Posted on by Lawrence Tabak, D.D.S., Ph.D.
As we get older, unfortunately our chances of having a stroke rise. While there’s obviously no way to turn back the clock on our age, fortunately there are ways to lower our risk of a stroke and that includes staying physically active. Take walks, ride a bike, play a favorite sport. According to our current exercise guidelines for American adults, the goal is to get in at least two and a half hours each week of moderate-intensity physical activity as well as two days of muscle-strengthening activity .
But a new study, published in the journal JAMA Network Open, shows that reducing the chances of a stroke as we get older doesn’t necessarily require heavy aerobic exercise or a sweat suit . For those who are less mobile or less interested in getting out to exercise, the researchers discovered that just spending time doing light-intensity physical activity—such as tending to household chores—“significantly” protects against stroke.
The study also found you don’t have to dedicate whole afternoons to tidying up around the house to protect your health. It helps to just get up out of your chair for five or 10 minutes at a time throughout the day to straighten up a room, sweep the floor, fold the laundry, step outside to water the garden, or just take a leisurely stroll.
That may sound simple, but consider that the average American adult now spends on average six and a half hours per day just sitting . That comes to nearly two days per week on average, much to the detriment of our health and wellbeing. Indeed, the study found that middle-aged and older people who were sedentary for 13 hours or more hours per day had a 44 percent increased risk of stroke.
These latest findings come from Steven Hooker, San Diego State University, CA, and his colleagues on the NIH-supported Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. Launched in 2003, REGARDS continues to follow over time more than 30,000 Black and white participants aged 45 and older.
Hooker and colleagues wanted to know more about the amount and intensity of exercise required to prevent a stroke. Interestingly, the existing data were relatively weak, in part because prior studies looking at the associations between physical activity and stroke risk relied on self-reported data, which don’t allow for precise measures. What’s more, the relationship between time spent sitting and stroke risk also remained unknown.
To get answers, Hooker and team focused on 7,607 adults enrolled in the REGARDS study. Rather than relying on self-reported physical activity data, team members asked participants to wear a hip-mounted accelerometer—a device that records how fast people move—during waking hours for seven days between May 2009 and January 2013.
The average age of participants was 63. Men and women were represented about equally in the study, while about 70 percent of participants were white and 30 percent were Black.
Over the more than seven years of the study, 286 participants suffered a stroke. The researchers then analyzed all the accelerometer data, including the amount and intensity of their physical activity over the course of a normal week. They then related those data to their risk of having a stroke over the course of the study.
The researchers found, as anticipated, that adults who spent the most time doing moderate-to-vigorous intensity physical activity were less likely to have a stroke than those who spent the least time physically active. But those who spent the most time sitting also were at greater stroke risk, whether they got their weekly exercise in or not.
Those who regularly sat still for longer periods—17 minutes or more at a time—had a 54 percent increase in stroke risk compared to those who more often sat still for less than eight minutes. After adjusting for the time participants spent sitting, those who more often had shorter periods of moderate-to-vigorous activity—less than 10 minutes at a time—still had significantly lower stroke risk. But, once the amount of time spent sitting was taken into account, longer periods of more vigorous activity didn’t make a difference.
While high blood pressure, diabetes, and myriad other factors also contribute to a person’s cumulative risk of stroke, the highlighted paper does bring some good actionable news. For each hour spent doing light-intensity physical activity instead of sitting, a person can reduce his or her stroke risk.
The bad news, of course, is that each extra hour spent sitting per day comes with an increased risk for stroke. This bad news shouldn’t be taken lightly. In the U.S., almost 800,000 people have a stroke each year. That’s one person every 40 seconds with, on average, one death every four minutes. Globally, stroke is the second most common cause of death and third most common cause of disability in people, killing more than 6.5 million each year.
If you’re already meeting the current exercise guidelines for adults, keep up the good work. If not, this paper shows you can still do something to lower your stroke risk. Make a habit throughout the day of getting up out of your chair for a mere five or 10 minutes to straighten up a room, sweep the floor, fold the laundry, step outside to water the garden, or take a leisurely stroll. It could make a big difference to your health as you age.
 How much physical activity do adults need? Centers for Disease Control and Prevention. June 2, 2022.
 Association of accelerometer-measured sedentary time and physical activity with risk of stroke among US adults. Hooker SP, Diaz KM, Blair SN, Colabianchi N, Hutto B, McDonnell MN, Vena JE, Howard VJ. JAMA Netw Open. 2022 Jun 1;5(6):e2215385.
 Trends in sedentary behavior among the US population, 2001-2016. Yang L, Cao C, Kantor ED, Nguyen LH, Zheng X, Park Y, Giovannucci EL, Matthews CE, Colditz GA, Cao Y. JAMA. 2019 Apr 23;321(16):1587-1597.
Stroke (National Institute of Neurological Disorders and Stroke/NIH)
REGARDS Study (University of Alabama at Birmingham)
NIH Support: National Institute of Neurological Disorders and Stroke; National Institute on Aging
Posted on by Dr. Francis Collins
As research on Alzheimer’s disease (AD) advances, a desperate need remains for an easy blood test to help diagnose the condition as early as possible. Ideally, such a test could also distinguish AD from other forms of dementia that produce similar symptoms. As published recently in Nature Medicine, an NIH-funded research team has designed a simple blood test that is on course to meet these criteria .
The latest work builds on a large body of work showing that one secret to predicting a person’s cognitive decline and treatment response in AD lies in a protein called tau. Using the powerful, but expensive, approach of PET scan imaging, we know that tau builds up in the brain as Alzheimer’s disease progresses. We also know that some tau spills from the brain into the bloodstream.
The trouble is that the circulating tau protein breaks down far too quickly for a blood test to offer a reliable measure of what’s happening in a person’s brain. A few years ago, researchers discovered a possible solution: test for blood levels of a slightly different and more stable version of the protein called pTau181 . (The “p” in its name comes from the addition of phosphorus in a particular part of the protein’s structure.)
In the latest study, researchers in the lab of Adam Boxer, University of California, San Francisco, followed up further on this compelling lead. Boxer’s team measured pTau181 levels in blood samples from 362 people between the ages of 58 and 70. Those samples included 56 people with an Alzheimer’s diagnosis, along with 47 people with mild cognitive impairment and 69 healthy controls.
The researchers also included another 190 people diagnosed with frontotemporal lobar degeneration (FTLD). It is a relatively rare form of dementia that leads to a gradual decline in behavior, language, and movement, often in connection with a buildup of tau in the brain.
The study found that levels of pTau181 were roughly 3.5-times higher in the blood of people with AD compared to people without AD. Those with mild cognitive impairment due to underlying AD also showed an intermediate increase in blood levels of pTau181.
Importantly, people with FLTD had normal blood levels of pTau181. As a result, the blood test could reliably distinguish between a person with AD and a person with FLTD. That’s important because, while FLTD is a relatively rare condition, its prevalence is similar to AD in people under the age of 65. But both conditions have similar symptoms, making it often challenging to distinguish them.
The findings add to evidence that the new blood test can help in diagnosing AD and in distinguishing it from other neurodegenerative conditions. In fact, it does so with an accuracy that often rivals more expensive PET scans and more invasive cerebrospinal fluid tests, which are now the only reliable ways to measure tau.
There’s still plenty of work to do before this blood test is ready for a doctor’s office. But these initial findings are very promising in helping to simplify the diagnosis of this devastating condition that now affects an estimated 5.5 million Americans .
 Diagnostic value of plasma phosphorylated tau181 in Alzheimer’s disease and frontotemporal lobar degeneration. Thijssen EH, La Joie R, Wolf A, Strom A, Wang P, Iaccarino L, Bourakova V, Cobigo Y, Heuer H, Spina S, VandeVrede L, Chai X, Proctor NK, Airey DC, Shcherbinin S, Duggan Evans C, Sims JR, Zetterberg H, Blennow K, Karydas AM, Teunissen CE, Kramer JH, Grinberg LT, Seeley WW, Rosen H, Boeve BF, Miller BL, Rabinovici GD, Dage JL, Rojas JC, Boxer AL; Advancing Research and Treatment for Frontotemporal Lobar Degeneration (ARTFL) investigators. Nat Med. 2020 Mar 2.
 Plasma phospho-tau181 increases with Alzheimer’s disease clinical severity and is associated with tau- and amyloid-positron emission tomography. Mielke MM, Hagen CE, Xu J, Chai X, Vemuri P, Lowe VJ, Airey DC, Knopman DS, Roberts RO, Machulda MM, Jack CR Jr, Petersen RC, Dage JL. Alzheimers Dement. 2018 Aug;14(8):989-997.
 Alzheimer’s Disease Fact Sheet. National Institute on Aging, May 22, 2019.
Alzheimer’s Disease & Related Dementias (National Institute on Aging/NIH)
Adam Boxer (University of California, San Francisco)
NIH Support: National Institute on Aging; National Institute of Neurological Disorders and Stroke; National Center for Advancing Translational Sciences
Posted on by Dr. Francis Collins
As many of us know from hard experience, tearing a muscle while exercising can be a real pain. The good news is that injured muscle will usually heal quickly for many of us with the help of satellite cells. Never heard of them? They are the adult stem cells in our skeletal muscles long recognized for their capacity to make new muscle fibers called myotubes.
This striking image shows what happens when satellite cells from mice are cultured in a lab dish. With small adjustments to the lab dish’s growth media, those cells fuse to form myotubes. Here, you see the striated myotubes (red) with multiple cell nuclei (blue) characteristic of mature muscle fibers. The researchers also used a virus to genetically engineer some of the muscle to express a fluorescent protein (green).