Association between the frequency of individual outdoor activity and risk of incident dementia in an elderly population in China: a national cohort study

Introduction: This study explored the association between the frequency of individual outdoor activity and the risk of incident dementia in an elderly population in China. We aimed to provide scientific evidence to support non-pharmaceutical strategies for preventing or delaying the onset of dementia. Methods: A total of 8,758 participants (median age: 85 years) from the Chinese Longitudinal Healthy Longevity Survey were included in the analyses. We assessed the association between the frequency of individual outdoor activity and the risk of incident dementia using the Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Subgroup analyses were performed, stratified by age, sex, and residence. Additionally, a sensitivity analysis was conducted to evaluate the robustness of the findings after excluding participants who, at baseline, had a Mini-Mental State Examination (MMSE) score <18 or had been diagnosed with stroke, other cerebrovascular diseases, diabetes mellitus, cancer, or Parkinson’s disease. Results: Over a median follow-up period of 4.33 years, 637 participants (7.27%) developed dementia. Compared with those who almost never engaged in outdoor activities, participants who engaged almost daily had a reduced risk of incident dementia by approximately 25% (HR: 0.75, 95% CI: 0.62–0.92). Subgroup analyses showed significant associations in females and participants living in cities and towns, whereas no significant differences were observed between age groups. The sensitivity analysis yielded results consistent with the primary analysis. Conclusion: Frequent participation in individual outdoor activity may be associated with a reduced risk of dementia among the elderly in China. These findings support outdoor activity as a potential non-pharmaceutical strategy to delay cognitive decline and prevent dementia.