Summary: A new analysis of data from the Framingham Heart Study indicates that regular physical activity is linked to larger brain volumes—particularly in the hippocampus—and a lower risk of developing dementia, with the strongest protective effect seen in adults aged 75 and older.
Source: UCLA
UCLA researchers used long-term Framingham Heart Study data to explore how physical activity relates to brain structure and dementia risk. Their findings associate low levels of physical activity with higher dementia risk among older adults and suggest that maintaining regular activity into late life may help preserve brain volume and reduce dementia risk.
The team observed that physical activity was especially tied to hippocampal volume, the region of the brain essential for short-term memory. The protective association between routine activity and lower dementia risk appeared strongest in participants aged 75 and above.
BACKGROUND
Previous studies examining the relationship between physical activity and cognitive decline, dementia, or Alzheimer’s disease have produced mixed results. To clarify this issue, researchers turned to the Framingham Heart Study, a long-standing, community-based study launched in 1948 that has tracked cardiovascular and neurological health across generations. For this investigation, UCLA researchers followed older participants from the Framingham Original and Offspring cohorts for more than a decade to evaluate how physical activity relates to the incidence of dementia and to MRI measures that indicate subclinical brain changes associated with dementia.
METHOD
The investigators assessed participants aged 60 and older from both the Framingham Original and Offspring cohorts, using a standardized physical activity index (PAI). The primary analysis included 3,714 cognitively intact participants (54% women; mean age 70 ± 7 years) to examine the relationship between PAI and the future risk of all-cause dementia and Alzheimer’s disease. A subset of roughly 1,987 participants from the Offspring cohort who had brain MRI data was also analyzed to determine how PAI related to structural brain measures, including total brain volume and hippocampal volume.
Over more than ten years of follow-up, incident dementia cases and Alzheimer’s disease diagnoses were recorded and analyzed in relation to baseline PAI. Statistical models adjusted for relevant demographic and clinical factors to estimate the association between physical activity levels and subsequent brain outcomes.
RESULTS
During the follow-up period, 236 participants developed dementia, 188 of whom were diagnosed with Alzheimer’s disease. Participants in the lowest quintile of physical activity showed a significantly greater risk of developing dementia compared with those in higher activity quintiles (hazard ratio = 1.50; 95% confidence interval = 1.04–1.97; p = .028) after adjustment for potential confounders. Secondary analyses indicated that the increased risk associated with low physical activity was primarily seen in individuals who did not carry the apolipoprotein E (APOE) ε4 allele, and the association was most pronounced among participants aged 75 and older. In the MRI subset, higher physical activity correlated linearly with greater total brain volume and larger hippocampal volume, supporting the idea that activity relates to preserved brain structure.
IMPACT
These results add to growing evidence that regular physical activity across the lifespan—and especially into older age—may provide measurable benefits for brain health. The study suggests two complementary mechanisms: a lower observed risk of developing dementia among more active older adults, and a positive association between activity levels and brain volume measures, particularly in the hippocampus. While observational in design and therefore unable to prove causation, the findings support public health messages encouraging sustained physical activity as a potentially modifiable factor that could contribute to maintaining cognitive health in later life.
Funding: This research received support from multiple National Institutes of Health grants and contracts, the National Institute on Aging, the National Institute of Neurological Disorders and Stroke, and the American Heart Association.
Original research: The analysis is reported in the paper “Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study” by Zaldy S. Tan, Nicole L. Spartano, Alexa S. Beiser, Charles DeCarli, Sanford H. Auerbach, Ramachandran S. Vasan, and Sudha Seshadri, published in Journals of Gerontology Series A: Biological Sciences and Medical Sciences (published online July 15, 2016).