Association of social network with the incidence of frailty and depressive symptoms among older adults: a two-year longitudinal study

BACKGROUND: Social isolation, which includes a limited social networks (SN) as one of its components, is a well-known risk factor for chronic conditions, including frailty and depression. However, associations between diverse SN and these conditions are not well understood. The aim of this study was to examine the associations between SN and frailty and depressive symptoms by gender, age, and economic status. METHODS: A two-year longitudinal study was conducted in Tsuru City, Yamanashi, Japan. Participants included all residents aged ≥65 years without physical disability (n = 3327). Surveys were conducted in January 2022 and January 2024. Frailty was assessed using the Kihon Checklist, depressive symptoms were evaluated by using the Geriatric Depression Scale-15, and SN was assessed using the Lubben Social Network Scale-6. Logistic regression models were conducted to compute odds ratios (OR) and 95 % confidence intervals (CI), stratified by gender, age, and economic status. RESULTS: During the follow-up period, 15.7 % of participants developed frailty, and 10.6 % developed depressive symptoms. Older adults in the highest SN group were less likely to develop frailty (OR [95 % CI]: 0.62 [0.43, 0.88]) and depressive symptoms (OR [95 % CI]: 0.58 [0.38, 0.89]) compared with those in the lowest SN group. Those associations were more pronounced in females, individuals aged <75 years, and those with poor economic status. CONCLUSIONS: Older adults with larger SN are less likely to develop frailty and depressive symptoms, particularly females, those aged <75 years, and those with poor economic status. This provides useful insights for future interventions.