Association between neighborhood socionatural environments and health satisfaction: a longitudinal mediation analysis

Neighborhood environments influence health in older adults; however, the mechanisms linking environmental factors to health outcomes remain insufficiently understood. In particular, few longitudinal studies have simultaneously examined the roles of social and natural environments and their potential pathways through health behaviors. This study aimed to investigate the longitudinal associations of neighborhood social and natural environments with health satisfaction in older adults and to examine whether physical activity mediates these relationships. This two-wave longitudinal study used data from a nationwide survey of community-dwelling older adults in Japan (baseline: 2023; follow-up: 2024). A total of 1,043 participants aged ≥ 65 years were analyzed. Social participation and perceived green space were used as indicators of social and natural environments, respectively. Physical activity was assessed as a potential mediator, and health satisfaction was the outcome variable (dichotomized at the median). Causal mediation analysis estimated the total effect (TE), natural direct effect (NDE), and natural indirect effect (NIE), adjusting for baseline health satisfaction and socioeconomic covariates. Among the participants, 432 (41.4%) were classified as having low health satisfaction and 611 (58.6%) as having high health satisfaction. Social participation was significantly associated with health satisfaction. The natural direct effect of social participation on health satisfaction was 0.099 (95% CI: 0.031-0.168), and the indirect effect mediated by physical activity was 0.017 (95% CI: 0.004-0.032). The total effect was 0.117 (95% CI: 0.046-0.189), and the proportion mediated by physical activity was 14.6%. In contrast, perceived green space showed a positive but non-significant association with health satisfaction. Social participation is longitudinally associated with higher health satisfaction, partially mediated by physical activity. These results highlight the importance of socionatural environmental design and community-led programs in promoting active lifestyles and health satisfaction among older adults.