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Researchers are trying to figure out why regular exercise seems to reduce the effects of Alzheimer’s disease. Getty Images
  • New studies are adding to a growing body of evidence that regular exercise can reduce Alzheimer’s symptoms.
  • One study reported that people over the age of 60 who do at least 30 minutes of exercise five days a week have fewer biomarkers associated with Alzheimer’s.
  • A second study found that people with a genetic high risk of Alzheimer’s who exercised regularly had fewer biomarkers.
  • A third study reported a biomarker known as “white matter hyperintensities” increased more slowly in people who are physically active.

The evidence linking exercise to a reduced risk for Alzheimer’s disease is growing.

New research presented today at the American Psychological Association’s annual meeting added to the tally of small studies that have found a correlation between physical activity and fewer signs or weaker symptoms of Alzheimer’s and other forms of dementia.

The question of whether the activity is the actual remedy remains open. But further, larger studies are moving forward to tackle the question.

If the answer is yes — and researchers can pinpoint exactly why exercise reduces risk — a door to new treatments could open.

The new studies focused on how moderate exercise is tied to “biomarkers” of Alzheimer’s.

These physical signs of the disease, such as the buildup of a protein called beta-amyloid in the brain, often show up before symptoms like memory loss.

In one paper, researchers compared information about people with parents who likely had Alzheimer’s. They found people older than 60 who reported getting at least 30 minutes of moderate exercise five days a week had fewer of those biomarkers and less decrease in memory and cognitive abilities.

Another study presented today looked at people deemed at high risk of Alzheimer’s because of certain genes.

It found fewer biomarkers among those who had better aerobic fitness based on their age, sex, body mass index, resting heart rate, and self-reported physical activity habits.

A third study found that one biomarker — known as “white matter hyperintensities” — was slower to increase in people who were deemed to have high levels of aerobic fitness.

Ozioma Okonkwo, PhD, an assistant professor of medicine at the University of Wisconsin who was an author on all three papers, said that taken together the findings suggest the effects of factors such as aging and genetics on Alzheimer’s risk may be able to be lessened by physical activity.

But he also cautioned the findings just found correlation between this activity and lowering these impacts. Further work is needed to see if exercise is really the reason.

The other caveat is these are small studies. They included 317, 95 and 107 participants.

The studies are “exciting and give some clues as to places to look into” in future research, Heather Snyder, PhD, director of medical and science operations at the Alzheimer’s Association, told Healthline.

But she noted that while the participants are relatively diverse, they are still relatively small studies.

That’s not uncommon.

“Most of the exercise studies have been relatively small,” she said.

But their numbers are growing.

A study published last year that found patients with a rare inherited, early onset form of Alzheimer’s who exercised for at least 2 1/2 hours a week had better cognitive performance and fewer signs of Alzheimer’s than those who didn’t.

It suggested the benefits from exercise seen in people with Alzheimer’s might hold for even those who are at the highest risk of developing the disease.

Other studies have also found that exercise has beneficial effects, including slowing the rate of cognitive decline in healthy people as well as those at risk of dementia and those who already have it.

And still other studies have concluded exercise may be tied to a reduced risk of developing Alzheimer’s.

To get firmer answers on causation will take more work.

“We’d need to (a) conduct longitudinal studies where people are followed over time to see how fitness — and change in fitness — tracks with change in [Alzheimer’s] biomarkers, and (b) conduct randomized controlled trials to examine how initiation of an exercise regimen in people who are currently inactive might affect [Alzheimer’s] biomarkers in the future,” Okonkwo told Healthline. “We are pursuing both avenues.”

The U.S. Pointer study organized by the Alzheimer’s Association may be the main way that’s happening.

The two-year clinical trial is evaluating whether lifestyle changes can preserve cognitive function in older people at risk of cognitive decline.

It’s a larger, more systematic way to study the effects of exercise as well as other factors.

“It’s looking ahead and identifying which lifestyle interventions may benefit brain health,” Snyder said.

The goal of the Pointer study “is to get us to the recommendations,” she said.

But she noted it also might open the door to new therapies beyond just a recommendation to exercise more.

Assuming exercise is a cause of reduced risk, then the key is identifying why that’s the case.

The most common theory is that there’s a benefit from exercise increasing the blood flow, which increases the amount of oxygen that gets to the brain.

There’s also the possibility of benefits from improvements in the metabolism of brain cells and from increases in certain hormones and proteins that are good for brain cells, as Okonkwo and Snyder both noted.

With that mechanism nailed down, “that really opens that door to try to get those benefits in other ways,” Snyder said.

That could be lifestyle changes such as exercise or a drug that mimics those benefits — or even a combination of benefits that can be added up and impact the brain in an even stronger way.

For now, Snyder said, “what seems consistent is that exercise is beneficial even if you’re already having cognitive decline. But you would need to discuss it with a healthcare provider before starting a new exercise regimen.”