Journal of the American Medical Directors Association · Nov 7, 2025

Replacement of Accelerometer-Measured Sedentary Behavior With Physical Activity Reduces Dementia Risk

By Yamaguchi R, Katayama O, Yamagiwa D et al.

OBJECTIVES: The mutual effects of different activity intensities in daily life, such as sedentary behavior (SB) and physical activity (PA), on dementia onset are not yet fully understood. The purpose of this study was to examine the association between replacing SB with PA and the risk of dementia in older adults by using the isotemporal substitution (IS) model. DESIGN: Prospective cohort study. SETTING AND PARTICIPANTS: Community-dwelling older adults living without dementia in Takahama, were enrolled, interviewed, and physically examined. Follow-up data were collected from the Japanese Public Health Insurance and/or Long-Term Care Insurance system databases during follow-up. METHODS: SB and PA data [light-intensity PA (LPA) and moderate-to-vigorous PA (MVPA)] were measured using a triaxial accelerometer for 14 days, and the average daily time for SB and PA was calculated in 10-minute increments. Participants were followed up monthly for new-onset dementia over 5 years. Cox proportional-hazards regression analysis was performed by using IS to estimate the effect of replacing one activity with another on the dementia onset. RESULTS: We included 1664 participants (mean ± standard deviation age, 73.1 ± 5.9 years) in this study. Over 5 years, 128 of 1664 participants developed dementia. Replacing 10 min/d of SB with LPA (hazard ratio, 0.86; 95% CI, 0.75-0.99) or MVPA (0.84; 0.74-0.96) was associated with a lower risk of dementia. CONCLUSIONS AND IMPLICATIONS: Replacing 10 minutes of SB with LPA or MVPA was associated with a lower risk of dementia. Feasible behavioral changes in daily life may lead to a healthy life expectancy.

doi.org/10.1016/j.jamda.2025.105972PubMed 41198035Populations