Effect Modification by Exercise Habit on the Association Between Participation in Community Gathering Places and Cognitive Disability

BACKGROUND: Community gathering places in Japan, supported by local governments, are expected to promote physical and cognitive health through physical activity and social interaction, in line with the World Health Organization's concept of age-friendly environments. However, evidence regarding their effects on dementia prevention remains inconsistent. This study aimed to assess whether habitual exercise modifies the association between participation in community gathering places and incident cognitive disability in older adults. METHODS: This retrospective cohort study used data from the Public Survey of Long-Term Care Prevention in Habikino City, Japan, and included community-dwelling adults aged ≥ 65 years without certified care needs. Participation in community gathering places was investigated at baseline and incident cognitive disability was tracked from January 2020 to January 2024. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) after adjusting for demographics and health status. To test the effect modification by exercise habit, product terms between participation and exercise status were included in the model. We addressed missing baseline data using multiple imputation. RESULTS: A total of 2758 eligible older adults were included in the primary analysis. We observed a potential effect modification by exercise habit status (p for interaction = 0.092). Participation in community-gathering places was associated with a lower hazard of cognitive disability among individuals without exercise habits (adjusted HR [95% CI], 0.51 [0.27, 0.97]), whereas no such association was observed among those with exercise habits (1.09 [0.57, 2.09]). CONCLUSIONS: The association between participation in community gathering places and cognitive disability may differ according to habitual exercise status. These findings suggest that municipally supported community gathering places may represent an accessible form of participation associated with a lower risk of cognitive disability among older adults without established exercise habits.