Community social capital and all-cause mortality in Japan: Findings from the Adachi Cohort Study

Background: Community social capital is associated with various health outcomes; however, its impact on mortality is not fully understood, particularly in non-Western settings. This study examined the association between community-level social capital and all-cause mortality among community-dwelling older Japanese adults. Methods: The baseline data were obtained from a 2015 questionnaire survey for all 132,005 residents aged >= 65 years without long-term care insurance certification in Adachi Ward (consisting of 262 small districts) of the Tokyo metropolitan area. We measured two aspects of social capital: neighborhood cohesion as cognitive social capital and neighborhood network as structural social capital. For district-level social capital, we aggregated the individual responses of neighborhood cohesion and neighborhood network in each district. Results: A total of 75,338 were analyzed. A multilevel survival analysis with an average follow-up of 1,656 days showed that higher district-level neighborhood cohesion was associated with a lower risk of all-cause mortality in men (hazard ratio [95% confidence interval]: 0.92 [0.84-0.99] for the highest quintile and 0.91 [0.82-0.99] for the second, compared to the lowest), not in women. This association was more pronounced in men aged 65-74 years. Conclusions: This study provides valuable insights from the Asian population. Men, who typically have fewer social networks and support systems than women, could receive more benefits from residing in a cohesive community, which may contribute to their longevity. These findings support public health strategies that bolster community social capital as a means of archiving longevity among older men, underscoring the importance of social integration in aging societies.