Role of Physical Activity in Protecting Against Dementia According to Menopausal Status.

BACKGROUND AND PURPOSE: This study evaluated the impact of physical activity on dementia risk in females while considering their menopausal status and body mass index (BMI) as potential modifiers.

METHODS

This population-based retrospective cohort study utilized the Korean National Health Insurance Service database, and stratified 2,163,842 females aged ≥40 years who underwent health examinations in 2009 into pre- and postmenopausal groups. Cox proportional-hazards models were used to estimate the adjusted hazard ratios (aHRs) for all-cause dementia, Alzheimer's dementia (AD), and vascular dementia (VaD) according to physical activity levels. Interaction terms were used to assess effect modification by BMI.

RESULTS

Regular physical activity was associated with a reduced risk of all-cause dementia and AD, but not VaD in premenopausal females (aHR=0.830, 95% confidence interval [CI]=0.739-0.931) and a reduced risk of all-cause dementia, AD, and VaD in postmenopausal females (e.g., aHR=0.884, 95% CI=0.868-0.900). The association between physical activity and dementia risk was largely consistent across BMI categories. However, a modest interaction was observed for light physical activity (LPA) (p=0.046), with a significant risk reduction in postmenopausal women with BMI ≥25.0 kg/m² (aHR=0.942, 95% CI=0.921-0.964).

CONCLUSIONS

Physical activity is associated with a lower risk of dementia in both pre- and postmenopausal females. Among postmenopausal females, even LPA such as walking may confer protective benefits, particularly in those with higher BMIs.