A Short Walk in the Park Might Slow Cognitive Decline in People at Risk of Developing Alzheimer’s
New research indicates that even moderate step counts, as low as 3,000 steps daily, were linked with delayed symptom onset
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Everyone knows that working out brings health benefits. New research, however, suggests that even moderate exercise might have benefits of its own, with just 3,000 steps a day linked with a slower progression of Alzheimer’s disease in at-risk patients.
The study, published November 3 in the journal Nature Medicine, found slower disease progression among older people at risk of developing the disease who walked between 3,000 and 7,500 steps a day.
While the study demonstrates an association and not a causal relationship, the results nevertheless inform one of medicine’s holy grails—preventing Alzheimer’s disease in aging patients.
Key takeaway: Diagnosing Alzheimer's disease
Usually, Alzheimer's disease is diagnosed after an individual begins to show signs of cognitive decline and memory loss starts affecting their daily life. But earlier detection is increasingly possible thanks to a better understanding of the disease's biomarkers and better imaging technology, per the Alzheimer's Association.“The very encouraging takeaway is that even a little bit of exercise seems to help,” Wai-Ying Wendy Yau, the first author of the study and a neurologist at Harvard Medical School, tells Nature‘s Mariana Lenharo. Yau tells the outlet that people can likely benefit even without hitting the popular goal of 10,000 steps per day—a level of activity that can be hard for some older people to achieve.
The research looked at daily physical activity and two brain proteins, amyloid-beta and tau, associated with Alzheimer’s disease. Yau and her colleagues used waistband pedometers to measure the physical activity of 296 participants aged 50 to 90 who did not initially have symptoms of cognitive decline, then looked for buildups of amyloid-beta and tau proteins with brain scans. All participants had yearly follow-up cognitive assessments for an average of 9.3 years, and some underwent additional scans to track the development of tau proteins.
Amyloid-beta and tau tend to accumulate abnormally in the brains of people with a heightened risk of developing Alzheimer’s, with amyloid-beta starting to increase first, as summarized by Nature.
The team found a connection between exercise and lower tau protein buildup, even in participants with higher initial levels of amyloid-beta.
“[Exercise is] somehow slowing the spread of this tau protein, which is more strongly associated with people developing symptoms [of Alzheimer’s disease] than amyloid-beta,” Charles Marshall, a dementia researcher at Queen Mary University of London who was not involved with the study, tells NewScientist‘s Carissa Wong.
Those with higher initial levels of amyloid-beta who walked 3,000 to 5,000 steps a day experienced an average delay of three years in cognitive decline, which increased to an average of seven years for those who walked 5,000 to 7,500 steps per day. Higher step counts were linked to both slower cognitive decline and slower accumulation of tau proteins.
On the other hand, tau proteins in the brains of inactive individuals accumulated significantly faster, and those patients also experienced faster declines in cognition and daily functioning. As for participants with low baseline levels of amyloid-beta, researchers documented very little cognitive decline or accumulation of tau proteins and no effect from exercise.
“We need randomized clinical trials to prove cause and effect, but it’s very encouraging that physical activity may help to modify someone’s trajectory,” Yau tells the Guardian‘s Ian Sample. “If they have amyloid, they could have a slower rate of decline if they’re more physically active.”
The results provide insight into why some people likely to develop Alzheimer’s disease don’t experience cognitive decline as rapidly as others, Jasmeer Chhatwal, senior author of the study and a neurologist at Massachusetts General Hospital, explains in a statement.
“Other studies have shown that different types of physical activity, beyond walking, [are] beneficial for brain health,” Yau explains to the Washington Post‘s Teddy Amenabar. “An important next step to look at is to clarify what aspects of physical activity—intensity, duration, pattern—[are] the most important in preclinical Alzheimer’s disease.”
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