Positive and Negative Effects of Finance-based Social Capital on Incident Functional Disability and Mortality: An 8-year Prospective Study of Elderly Japanese

BACKGROUND Rotating savings and credit associations (ROSCAs) involve group financial self-help activities. These voluntary financial cooperative associations-mujin in Japanese-are found in some rural areas of Japan. Cross-sectional evidence suggests that active participation in mujin correlates with rich social capital and better functional capacities among older adults. However, the effect of mujin on subsequent health outcomes is unknown. METHODS In 2003, we conducted a baseline interview survey of 583 functionally independent adults randomly selected from Yamanashi Prefecture residents aged 65 years or older. They were followed up until 2011. We used proportional hazards models, and factor analysis of 8 mujin-related questions identified 2 components: the "intensity and attitude" and "financing" aspects of mujin. RESULTS The hazard ratios (HRs) for incident functional disability-identified by using the public long-term care insurance database-per 1-SD increase in factor scores were 0.82 (95% CI: 0.68-0.99) for the intensity and attitude score and 1.21 (1.07-1.38) for financing score. Adjustments for age, sex, marital status, household composition, physical health, education, income, and other factor scores only slightly attenuated these HRs. The results for mortality models were very similar to those for incident functional disability. CONCLUSIONS ROSCA-type activities in Japan could have beneficial effects on the health of older adults if used primarily for the purpose of friendship. Mujin for aggressively financial purposes might be somewhat harmful, as such activities might reflect the "dark side" of social capital, ie, overly demanding expectations of group conformity.