Few realities of aging are scarier than the possibility that you might someday be diagnosed with dementia.
Such fears are well-founded. More than 7 million Americans have Alzheimer’s disease, according to the Alzheimer’s Association. By 2050, that number is expected to nearly double to 13 million.
Anything a person can do to avoid or slow cognitive decline is worth considering. Recent research has suggested several ways to protect your brain, including boosting your heart health, reducing anxiety and even simply developing more purpose in your life.
People who have elevated levels of the protein amyloid-beta in their brain are known to be at higher risk for Alzheimer’s. Now, a study suggests that even a modest increase in walking might slow the progression of the disease in these folks.
Researchers at Mass General Brigham found that walking between 3,000 and 5,000 steps per day was associated with a three-year delay in cognitive decline on average. Pushing the daily number of steps to between 5,000 and 7,500 was associated with an even longer delay of seven years.
Mass General Brigham is a Boston-based health care system affiliated with Harvard Medical School.
The researchers’ findings were published in the scientific journal Nature Medicine.
Why is walking so helpful? The researchers say those who remain sedentary have a much faster buildup of tau, another protein tied to Alzheimer’s risk, and more rapid declines in cognition and daily functioning.
In a summary of the study findings, senior author Dr. Jasmeer Chhatwal of the Mass General Brigham Department of Neurology says:
“This sheds light on why some people who appear to be on an Alzheimer’s disease trajectory don’t decline as quickly as others. Lifestyle factors appear to impact the earliest stages of Alzheimer’s disease, suggesting that lifestyle changes may slow the emergence of cognitive symptoms if we act early.”
As part of the study, researchers looked at medical data on 296 people between the ages of 50 and 90 who were in the Harvard Aging Brain Study. None of these folks had cognitive impairment at the beginning of the study.
Researchers used brain scans to measure baseline levels of amyloid-beta and tau. They also monitored the participants’ physical activity via waistband pedometers.
Participants also took annual cognitive assessments for 9.3 years on average. A subset of participants received repeated brain scans to look for changes in tau.
Among those who had elevated levels of amyloid-beta at the outset of the study, taking more steps was associated with a slower rate of cognitive decline and a slower buildup of tau proteins.
Among folks who had low levels of amyloid-beta at the outset, there was “very little” cognitive decline or accumulation of tau proteins over time, the researchers said. For this group, physical activity did not appear to play a significant role in their risk of Alzheimer’s.
The research suggests the benefits of physical activity that are associated with slower cognitive decline are driven by slower buildup of tau specifically.