Association between social interactions and motor function in community-dwelling older Japanese adults

This longitudinal observational study examined the association between multidimensional social interaction and motor function among community-dwelling older Japanese adults over a 9-year follow-up period (2011–2020). Using data from the Community Empowerment and Care Cohort Study in suburban central Japan, the analysis included 304 participants aged 65 years and older who had no baseline motor impairment and completed follow-up. Social interaction was assessed using the Index of Social Interaction (ISI), and motor function was evaluated using the Kihon Checklist. After adjustment for age, IADL status, and baseline motor function score, higher total ISI was significantly associated with higher odds of having normal motor function at follow-up (odds ratio [OR]: 1.21; 95% confidence interval [CI]: 1.01–1.47; p = 0.044). Among the ISI subscales, social curiosity showed a significant association with motor function at follow-up (OR: 1.39; 95% CI 1.01–1.92; p = 0.045). These findings suggest that baseline social interaction, particularly social curiosity, may be a relevant predictive factor for later motor function among community-dwelling older adults. However, because the analysis was observational and conditioned on survival and continued participation, the findings should be interpreted as predictive associations rather than causal effects.