A modest increase in daily steps could slow the progression of Alzheimer’s disease for people at higher risk, new research shows. In a study published in Nature Medicine, Mass General Brigham researchers found that higher physical activity levels were linked to slower cognitive decline in older adults with elevated amyloid-beta, a protein associated with Alzheimer’s.
Key findings indicate that cognitive decline was delayed by about three years for participants who walked 3,000 to 5,000 steps per day, and by around seven years for those who walked 5,000 to 7,500 steps daily. Participants who led sedentary lives showed a faster buildup of tau proteins in the brain and steeper declines in cognition and daily functioning.
These results shed light on why some individuals who seem to be on an Alzheimer’s disease trajectory do not decline as rapidly as others. The researchers suggest that lifestyle factors influence the earliest stages of the disease and that early, proactive changes may slow the appearance of cognitive symptoms.
Study details and methods
The Harvard Aging Brain Study provided data for 296 participants aged 50 to 90 who were cognitively unimpaired at the outset. Baseline amyloid-beta plaques and tau tangles were measured with PET brain scans, while physical activity was tracked with waistband pedometers. Participants underwent annual cognitive assessments for two to 14 years, with an average follow-up of 9.3 years. A subset also received repeated PET scans to monitor tau changes over time.
The association between steps and brain health
Higher step counts correlated with slower cognitive decline and a reduced rate of tau buildup among those with elevated baseline amyloid-beta. The study’s statistical models indicated that most of the cognitive benefits of physical activity came from slower tau accumulation. In contrast, among participants with lower amyloid-beta at baseline, there was minimal cognitive decline and little tau accumulation, and physical activity showed no significant association with cognitive outcomes.
Expert commentary and implications
Co-author Reisa Sperling, MD, of Mass General Brigham and a co-principal investigator of the Harvard Aging Brain Study, said the findings reinforce the importance of physical activity for maintaining brain health. She noted that these results demonstrate a path to cognitive resilience and resistance to tau pathology in the preclinical phase of Alzheimer’s disease. The research offers cautious optimism for strategies aimed at preventing Alzheimer’s dementia and reducing dementia driven by multiple factors.
Conclusion
Researchers plan to explore which aspects of physical activity matter most, such as exercise intensity and patterns of activity over time. They also aim to uncover the biological mechanisms linking physical activity, tau buildup, and cognitive health. The team hopes that these insights will guide future clinical trials testing exercise interventions to slow late-life cognitive decline, especially for individuals at higher risk due to preclinical Alzheimer’s disease.
“Every step counts,” said Wai-Ying Wendy Yau, MD, the study’s first author and a cognitive neurologist at Mass General Brigham. “Small increases in daily activity can accumulate over time to produce lasting improvements in habits and health, empowering people to protect their brain and cognitive function.”
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