Accelerometer-Measured Sedentary Behavior Patterns, Brain Structure, and Cognitive Function in Dementia-Free Older...

Area of Science:

• Neuroscience
• Gerontology
• Public Health

Background:

• Sedentary behavior is a known risk factor for cognitive impairment.
• The underlying neuropathological mechanisms linking sedentary behavior and cognitive decline are not well understood.

Purpose of the Study:

• To examine the relationship between sedentary behavior patterns and brain structure and cognition in older adults.
• To explore potential mediating mechanisms, including brain structural markers.

Main Methods:

• A community-based study of 2,019 older adults (≥60 years) without dementia.
• Sedentary behavior assessed via accelerometers; cognitive function via neuropsychological tests.
• Brain MRI scans analyzed in a subsample (n=1,009) using general linear, isotemporal substitution, and mediation models.

Main Results:

• Longer sedentary bout duration correlated with lower global cognition, verbal fluency, and memory.
• Greater total sedentary time was associated with poorer cognition only in those with >10 hours/day of sedentary time.
• Interrupting sedentary time with light physical activity improved verbal fluency and memory.
• Structural brain markers partially mediated the association between sedentary bout duration and cognitive function.

Conclusions:

• Prolonged, uninterrupted sedentary time is associated with diminished cognitive function in older adults.
• Structural brain changes may partially explain how sedentary behavior impacts cognition.
• Strategies to reduce prolonged sedentary time and incorporate light activity are important for cognitive health in aging.