Association between physical activity and incident dementia among individuals with hypertension.

OBJECTIVES

Evidence on the association between physical activity (PA) and incident dementia among individuals with hypertension remains limited. This study examined the associations between different PA types and intensities and dementia risk in this population.

METHODS

Data from questionnaire-based and accelerometer-based cohorts were analyzed. PA was categorized into quartiles of light-intensity (LPA), moderate-intensity (MPA), vigorous-intensity (VPA), moderate-to-vigorous-intensity PA (MVPA), and total PA (TPA). PA domains included leisure time, housework, transportation, and occupational activities. Incident dementia was identified using hospital inpatient and death records, which may not capture milder dementia cases and classified as early- or late-onset by age at diagnosis. Cox proportional hazards models were used.

RESULTS

In the accelerometer-based cohort of 47,861 hypertensive participants, 574 (1.2%) developed dementia over a median of 8.1 years. Compared with the lowest quartile, the highest quartile of MPA (HR 0.41, 95% CI 0.31-0.54), VPA (HR 0.34, 95% CI 0.25-0.46), MVPA (HR 0.43, 95% CI 0.32-0.57), and TPA (HR 0.63, 95% CI 0.49-0.82) had lower risks of incident dementia. In the questionnaire-based cohort, 5,647 (2.5%) cases occurred over a median of 13.7 years. Higher PA levels, particularly leisure-time and housework-related PA, were consistently tied to a lower risk estimate. MPA showed a more pronounced risk reduction for early-onset than late-onset dementia (ratio of HR 0.69, 95% CI 0.50-0.96).

CONCLUSION

Higher levels of MPA, MVPA, VPA, and TPA are associated with a lower risk profile for dementia among individuals with hypertension, with variations observed across activity domains and age of onset. However, the reliance on hospital and death records for dementia ascertainment may underestimate the true burden by missing milder cases. These findings demonstrate associations rather than causal effects and require confirmation in intervention studies.