Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study

Area of Science:

• Neuroscience
• Gerontology
• Public Health

Background:

• Longitudinal studies suggest a link between physical activity and cognitive health, but findings are inconsistent.
• Research is needed to clarify the association between physical activity and cognitive decline, dementia, and Alzheimer's disease (AD).

Purpose of the Study:

• To investigate the association between physical activity levels and the risk of incident dementia.
• To examine the relationship between physical activity and subclinical brain magnetic resonance imaging (MRI) markers of dementia.

Main Methods:

• The Framingham Study Original and Offspring cohorts, comprising individuals aged 60 years and older, were analyzed.
• Physical Activity Index (PAI) was assessed, and its association with dementia and AD risk was examined in 3,714 cognitively intact participants.
• Brain MRI was additionally analyzed in 1,987 participants from the Offspring cohort.

Main Results:

• Participants with the lowest PAI showed a significantly increased risk of dementia (HR=1.50, p=.028).
• This association was more pronounced in noncarriers of the apolipoprotein (APO)E ε4 allele and individuals aged 75 years and older.
• Higher PAI was linearly associated with greater total brain and hippocampal volumes.

Conclusions:

• Low physical activity is linked to an elevated risk of dementia in older adults.
• Maintaining physical activity in later life may be a strategy to reduce dementia risk and support brain health.
• Higher physical activity is associated with larger brain volumes, suggesting neuroprotective benefits.