A “moderate” amount of physical activity—in the form of getting your daily steps—could be help slow Alzheimer’s disease among those at risk.
This is the finding of Mass General Brigham scientists who determined that a surprisingly achievable step count was associated with slower rates of cognitive decline in older adults with elevated levels of amyloid beta, a protein linked to the disease.
Cognitive decline was delayed by three years on average for people who walked just 3,000–5,000 steps per day, according to the 14-year study of cognitively unimpaired older adults.
Meanwhile, it was delayed by seven years for people who walked 5,000–7,500 steps per day.
Those who were sedentary, however, had a significantly faster harmful buildup of tau proteins in the brain and more rapid declines in cognition and daily functioning.
“We were able to clarify that the association with cognitive decline was not explained by differences in amyloid accumulation,” study author and cognitive neurologist Dr. Wai-Ying Wendy Yau told Newsweek.
“Instead, for a given amount of elevated amyloid burden, 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.”
“This [study] sheds light on why some people who appear to be on an Alzheimer’s disease trajectory don’t decline as quickly as others,” said study author and neurologist Dr. Jasmeer Chhatwal in a statement.
“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.”
“These findings show us that it’s possible to build cognitive resilience and resistance to tau pathology in the setting of preclinical Alzheimer’s disease,” added study author and neurologist Dr. Reisa Sperling.
“This is particularly encouraging for our quest to ultimately prevent Alzheimer’s disease dementia, as well as to decrease dementia due to multiple contributing factors.”
The team analyzed data on 296 cognitively unimpaired participants aged 50–90 in the Harvard Aging Brain Study.
“This research provides strong evidence that moderate levels of physical activity are associated with slower progression of the earliest stages of Alzheimer’s disease and that this is linked to slower accumulation of tau protein, which is an important cause of brain cell loss,” said neurologist professor Charles Marshall of Queen Mary University of London—who was not involved in the study—in a statement.
The researchers used PET brain scans to measure baseline levels of amyloid-beta in plaques (dense clumps) and tau in tangles (formed from the accumulation of abnormal tau) and assessed the participants’ physical activity using small waistband tracking devices.
The main study group received annual follow-up cognitive assessments for between two and 14 years while a subset group received repeated PET scans to track changes in tau.
More steps were linked to slower rates of cognitive decline and a slower buildup of tau proteins. In people with low baseline levels of amyloid-beta, however, there was very little cognitive decline or accumulation of tau proteins over time and no significant associations with physical activity.
“With this type of observational study, it is always hard to be sure whether the physical activity is actually the thing causing the observed difference. The authors do a good job of trying to disentangle this, but we cannot be certain whether the people doing more exercise are healthier in other ways, nor whether the development of Alzheimer’s disease changes are influencing activity levels (reverse causality),” said Marshall.
“We also cannot be sure that it is physical activity during this period in later life that makes the difference, or whether those who are more active now have been more active for decades and that the benefits accrue in the much longer term.”
“The study followed people with raised levels of amyloid in their brain—a potential early sign of Alzheimer’s—but who were not cognitively impaired. We don’t know if these people went on to develop dementia or whether walking 5,000–7,000 steps a day might reduce the risk of or prevent the condition,” added Richard Oakley, associate director of research and innovation at Alzheimer’s Society in the UK, in a statement.
“We would encourage everyone to exercise regularly if they can. Other steps like eating a healthy balanced diet, not smoking, drinking less alcohol and keeping on top of health conditions, such as diabetes or high blood pressure, can also help reduce our risk of getting dementia.”
The researchers next plan to look into both which aspects of physical activity—like intensity and longitudinal activity—may be most important and the biological mechanisms linking physical activity, tau buildup and cognitive health. This collective work may help design future clinical trials that test exercise interventions to slow late-life cognitive decline, according to the authors.
“Every step counts—and even small increases in daily activities can build over time to create sustained changes in habit and health,” added Yau.
Do you have a tip on a health story that Newsweek should be covering? Do you have a question about Alzheimer’s? Let us know via health@newsweek.com.
Reference
Yau, W.-Y. W., Chhatwal, J. P., & colleagues. (2025). Physical activity as a modifiable risk factor in preclinical Alzheimer’s disease. Nature Medicine. https://doi.org/10.1038/s41591-025-03955-6