Although results have been inconsistent, several studies indicate an inverse relationship between physical activity levels and cognitive decline, dementia, and/or Alzheimer’s disease (AD). Therefore, in order to examine the association of physical activity with the risk of incident dementia and subclinical brain MRI markers of dementia, researchers followed an older, community-based cohort for over a decade. Using the Framingham Study Original and Offspring cohorts (aged 60 yrs and older) the physical activity index (PAI) was assess. Researchers examined the link between PAI and risk of incident all-cause dementia and AD in participants of both cohorts who were cognitively intact and had available PAI. They also examined the association between PAI and brain MRI in the Offspring cohort. Over a decade of follow-up, in a multivariable adjusted model, participants in the lowest quintile of PAI had an increased risk of incident dementia compared with those in higher quintiles. Secondary analysis revealed that this relation was limited to participants who were apolipoprotein (APO)E є4 allele non-carriers, and strongest in participants aged 75 years and older. PAI was also linearly related to total brain and hippocampal volumes. The researchers concluded that low physical activity is associated with a higher risk for dementia in older individuals, suggesting that a reduced risk of dementia and higher brain volumes may be additional health benefits of maintaining physical activity into old age.
Tan ZS, et al. Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 2016 (First published online: July 15, 2016)