田中 笑子

OBJECTIVE: This study aimed to explore the direct and indirect effects of social frailty on functional state trajectories mediated by subjective cognitive function in older adults. DESIGN: Longitudinal study. SETTING AND PARTICIPANTS: Overall, 514 adults aged ≥65 years living in a suburban area of central Japan were included in this study. METHODS: Five-item social frailty index (going out, visiting, feeling helpful, living alone, and talking to others), subjective cognitive function from the Kihon Checklist, and instrumental activities of daily living disability. Latent growth curve models were applied to examine the longitudinal relations among the variables. RESULTS: During the 6-year follow-up in latent growth curve models, the initial level of social frailty in older adults was negatively associated with that of functional status (β = -0.53, P < .001), and the rate of change in social frailty was negatively associated with that in functional status (β = -0.78, P < .001). In the mediation model, the indirect effect from the social frailty level to functional status level through subjective cognitive function level was significant (β = -0.14, 95% CI -0.29, -0.09); the rates of change in subjective cognitive function mediated the relationship between those in social frailty and functional status (β = -0.35, 95% CI -0.46, -0.25). CONCLUSIONS AND IMPLICATIONS: This study found that there is an association between social frailty and functional status in Japanese older adults. Subjective cognitive function mediated this relationship. Hence, additional research is required to investigate additional potential factors linking social frailty and functional status in order to gain a better understanding of the underlying mechanisms.

OBJECTIVES: This study aimed to explore the bidirectional association between frailty and social relationships in older adults while distinguishing between interpersonal and intrapersonal effects. METHODS: A prospective cohort study of community-dwelling older adults was conducted in Japan in three waves spanning six years with follow-ups in every three years. Random intercept cross-lagged panel model was used to explore temporal associations between frailty and social relationships. RESULTS: Data for 520 participants (mean age 73.02 [SD 6.38] years, 56.7% women) were analyzed. Across individuals, frailty was associated with social relationships (β = -0.514, p < 0.001). At the interpersonal level, frailty was cross-sectionally associated with social relationships separately at T1(β = -0.389, p < 0.01), T2 (β = -0.343, p < 0.001) and T3 (β = -0.273, p < 0.05). Moreover, social relationships were associated with subsequent increases in symptoms of frailty in all measurement waves (β = -0.332, p < 0.001; β = -0.169, p < 0.01) and vice versa (β = -0.149, p < 0.05; β = -0.292, p < 0.001). CONCLUSIONS: The results suggest that frailty was associated with lower levels of social relationships. Frailty improvement programs can be combined with interventions to enhance social relationships, which will be beneficial in preventing frailty. The results emphasize the importance of combining clinical treatments of frailty with interventions to improve social relationships.