Recent research reveals that individuals who walked between 3,000 and 5,000 steps daily experienced a significant delay of approximately three years in cognitive decline. Furthermore, those who increased their daily step count to between 5,000 and 7,500 steps saw this delay extend to around seven years. In stark contrast, participants who led a largely inactive lifestyle exhibited a quicker accumulation of tau proteins in the brain, a key factor associated with the progression of Alzheimer's disease, along with a more rapid decline in cognitive abilities and daily functioning. This highlights a critical question: why do some individuals on a trajectory towards Alzheimer’s show slower decline than others? According to senior author Jasmeer Chhatwal, MD, PhD, from the Mass General Brigham Department of Neurology, the answer lies in the influence of lifestyle factors on the earliest stages of Alzheimer’s. The findings suggest that making lifestyle changes early on could potentially slow the onset of cognitive symptoms.
The study focused on 296 individuals aged between 50 and 90, all of whom displayed no cognitive impairment at the beginning of the Harvard Aging Brain Study. Participants utilized waistband pedometers to monitor their physical activity levels and underwent PET scans to evaluate the presence of amyloid-beta plaques and tau tangles in the brain. Annual cognitive assessments were conducted over a period ranging from two to 14 years, with an average duration of 9.3 years. A subset of participants also received additional brain scans to track changes in tau over time. The results were compelling: those with elevated amyloid-beta levels who engaged in higher daily step counts experienced a slower cognitive decline and a reduced buildup of tau proteins. Statistical modeling indicated that the primary advantage of physical activity was its correlation with slower tau accumulation.
Interestingly, among participants with low amyloid-beta levels, there was minimal evidence of cognitive decline or tau buildup, indicating no significant connection between activity levels and cognitive health in this group.
Co-author Reisa Sperling, MD, a neurologist at Mass General Brigham and co-principal investigator of the Harvard Aging Brain Study, expressed enthusiasm about how data from this study enhances our understanding of the role of physical activity in maintaining brain health. These findings suggest that it is indeed feasible to foster cognitive resilience and combat tau pathology even in the preclinical stages of Alzheimer’s disease. This is particularly promising for the ultimate goal of preventing Alzheimer’s dementia and reducing dementia linked to various contributing factors. The research team plans to delve deeper into which specific types of physical activities offer the most benefits, including the effects of intensity and long-term exercise patterns on brain health.
Additionally, researchers aim to identify the biological mechanisms that intertwine physical activity, tau accumulation, and cognitive function. These insights may pave the way for future clinical trials exploring whether exercise-based interventions can effectively slow cognitive decline in older adults, especially those at a heightened risk for Alzheimer’s.
First author Wai-Ying Wendy Yau, MD, a cognitive neurologist at Mass General Brigham, emphasized the importance of empowering individuals to safeguard their brain and cognitive health through regular physical activity. “Every step counts,” she noted, highlighting that even minor increases in daily activity can accumulate over time, leading to meaningful changes in habits and health outcomes.
The study’s authors, including Dylan R. Kirn, Michael J. Properzi, Aaron P. Schultz, Zahra Shirzadi, Kailee Palmgren, Paola Matos, Courtney Maa, Stephanie A. Schultz, Rachel F. Buckley, Dorene M. Rentz, and Keith A. Johnson, along with Jennifer S. Rabin and Jeremy J. Pruzin, have no competing interests related to the current study. Funding for this vital research was provided by the National Institutes of Health and the Doris Duke Charitable Foundation Clinical Scientist Development Award, among others.
