Frailty Through a One Health Lens: Biological Sex, Mental Health, and Oral Function in Physically Active Older Adults

Frailty is a multifactorial geriatric syndrome marked by reduced physiological reserves and increased vulnerability to adverse outcomes. This multicenter observational study adopted a One Health approach to examine the association between frailty and biological sex, denture use, and antidepressant medication, as well as their impact on bite force, in two transnational cohorts of physically active older adults. The sample included 499 individuals aged ≥60 years (295 from Brazil and 204 from Portugal), all with functional dentition and regular physical activity. Frailty was assessed using the adapted Fried phenotype and classified as non-frail (G0), pre-frail (G1), or frail (G2). Oral health, depressive symptoms (CES-D), bite force, and self-reported use of dentures and antidepressants were analyzed. Frailty was significantly associated with biological sex (p < 0.001), with higher prevalence among women, especially in G2. Antidepressant use was associated with frailty in the Portuguese cohort (p < 0.001) and in the total sample (p = 0.005), but not in Brazil. No significant association was observed between denture use and frailty. However, Brazilian participants without dentures showed significantly higher bite force (p < 0.001), indicating a functional oral health effect. Frailty was associated with female sex and antidepressant use, while bite force emerged as a complementary functional marker for geriatric assessment.