“This is encouraging and suggests that even small, consistent increases in daily activity among sedentary individuals may be meaningful for brain health, although clinical trials will be needed to confirm these observational findings,” says the first study author, Wai-Ying Wendy Yau, MD, a cognitive neurologist at the Mass General Brigham neurology department in Boston.
How Many Steps a Day Do You Need to Protect Your Brain?
Researchers analyzed health data from about 300 adults between ages 50 and 90 whose brain scans revealed early biological markers of Alzheimer’s disease. At the beginning of the study, they wore pedometers over four to seven days to measure daily steps. At that time, none displayed any symptoms of cognitive impairment.
Over a follow-up of up to 14 years, researchers assessed participants periodically with cognitive tests. Participants also underwent brain imaging to monitor for the buildup of proteins known as beta-amyloid and tau that are connected to Alzheimer’s disease progression.
The results showed that participants who began the trial with high levels of beta-amyloid experienced less cognitive decline if they were more physically active.
Participants who engaged in low or moderate levels of physical activity had a lower risk of cognitive decline — up to 54 percent lower — than participants who reported being inactive.
Here’s what the team found.
- In people who walked 3,000 to 5,000 steps per day, cognitive decline was delayed by three years on average.
- In people who walked 5,000 to 7,500 steps per day, cognitive decline was delayed by an average of seven years.
- More than 7,500 steps didn’t appear to make a difference in slowing cognitive decline.
- People with a sedentary lifestyle had a significantly faster buildup of tau proteins in the brain, and quicker declines in cognition and daily functioning.
One potential study limitation is that researchers only measured participants’ physical activity once, at baseline, using pedometer-measured step counts over four to seven days. They did not collect data over the course of the week on factors such as exercise intensity.
“The results of the association analyses must be interpreted with great caution,” says Martin Burtscher, MD, PhD, a professor of sports science at the University of Innsbruck in Austria who has researched the relationship between exercise and longevity, including age-related cognitive decline, who was not involved in the current study.
The Link Between Exercise and Brain Changes That Lead to Cognitive Decline
By using direct measures of amyloid and tau in the brain, rather than cognitive symptoms, Yau says this latest study was able to clarify that the physical activity benefits associated with slowed cognitive decline were not attributed to differences in amyloid buildup — but rather connected to slower rates of tau protein buildup.
“Higher step counts were associated with slower accumulation of tau, the protein most closely tied to cognitive symptoms — which largely accounted for the association with slower cognitive decline,” she explains.
Taking Steps to Improve Cognitive Health
Dr. Burtscher says that while the latest findings aren’t necessarily surprising given previous associations between regular physical activity and improved physical and mental health, they’re key for underscoring a more attainable physical activity goal — particularly for sedentary individuals.
“What impressed me most is the dose–response,” Burtscher says. “Cognitive decline hit a plateau at a moderate level of physical activity, or 5,001–7,500 steps per day. This is a relatively easy daily amount of physical activity to achieve.”
What’s Next for Alzheimer’s Prevention Research
The study authors say clinical trials are still needed to prove that walking, rather than other behaviors, is responsible for the slowed rate of cognitive decline. They also say additional research is needed to better understand the specific aspects of physical activity — such as duration, intensity, or daily patterns — that go into supporting long-term brain health.
Yau says she hopes the findings will motivate people to make small, sustainable changes to increase their physical activity to potentially improve brain health.
“For people who are currently sedentary, every additional step counts,” she says. “Setting modest and realistic goals, such as standing up and walking during TV commercials, parking a little farther away, or catching up with a friend on a walk instead of sitting down, can help increase activity in simple, sustainable ways.”
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