Mediating role of malnutrition in the associations between oral frailty, food insecurity, and depression among rural older adults: an exploratory model-based analysis.

BACKGROUND: Depression is a growing concern among rural older adults and is associated with factors such as oral frailty and food insecurity, with malnutrition possibly contributing to these associations. This study aimed to examine malnutrition as a potential statistical mediator in the associations between oral frailty, food insecurity, and depression within a biopsychosocial perspective, using an exploratory, model-based approach. METHODS: This cross-sectional study enrolled 327 community-dwelling older adults from three rural provinces of Türkiye. Oral frailty was assessed using the Oral Frailty Index-8 (OFI-8), food insecurity using the Food Insecurity Experience Scale (FIES), malnutrition using the Mini Nutritional Assessment-Short Form (MNA-SF), and depression using the Geriatric Depression Scale-30 (GDS-30). Multiple logistic regression and bootstrap mediation analyses (5,000 resamples), with malnutrition as the hypothesized mediator, were performed adjusting for age, gender, income, living arrangement, and IADL score. RESULTS: The median age was 64 [interquartile range (IQR): 61-70] years, 58.4% were female. Depressive symptoms were identified in 34.9% of participants. Oral frailty [OR (95% CI) = 1.964 (1.452-2.658), p < 0.001], food insecurity [OR (95% CI) = 1.381 (1.066-1.790), p = 0.015], and malnutrition [OR (95% CI) = 1.949 (1.538-2.469), p < 0.001] were significantly associated with depression after adjusting for potential confounders (age, gender, living arrangement, income, IADL score). Mediation analysis revealed that malnutrition mediated approximately 23.6% of the total effect of oral frailty on depression (total effect β = 0.055, 95% CI: 0.025-0.087, p = 0.002) and 22.0% of the total effect of food insecurity (total effect β = 0.050, 95% CI: 0.020-0.085, p = 0.002). CONCLUSION: Malnutrition significantly associated with oral frailty, food insecurity, and depression in rural older adults. Integrated interventions targeting nutrition, oral health, and food security may be beneficial in mitigating depression risk in this vulnerable population.