Oral Frailty and the Trajectories of Psychological Well-being and Cognitive Function: Findings from the 12-Year Community-based Kashiwa Study

Background Oral frailty may be associated with adverse health outcomes; however, its long-term impact on psychological well-being and cognitive function remains unclear. We aimed to examine the longitudinal association between oral frailty and trajectories of subjective well-being, depressive symptoms, and cognitive function in community-dwelling older adults. Methods We conducted a 12-year prospective cohort study of community-dwelling adults aged ≥65 years in Kashiwa, Japan. Oral frailty was assessed using items corresponding to Oral Frailty 5-item checklist (OF-5). Outcomes included the World Health Organization-Five Well-Being Index, Geriatric Depression Scale-5, Mini-Mental State Examination (MMSE) and mild cognitive impairment (MCI), operationally defined as a screening-based outcome using an MMSE cut-off ≤27. All OF-5 components and outcomes were measured across seven waves (2012–2024). Generalized linear mixed-effects models were used to examine longitudinal associations. Results A total of 1,679 participants (mean age 72.7 ± 5.5 years, 49.5% female) were included. Baseline oral frailty was associated with lower subjective well-being (adjusted β = −0.47; 95% CI: −0.77 to − 0.17) and higher depressive symptoms (adjusted β = 0.13; 95% CI: 0.06 to 0.19), while time-varying oral frailty showed consistent concurrent associations with both outcomes. Only baseline oral frailty was associated with an increased risk of MCI (adjusted risk ratio, 1.29; 95% CI: 1.13 to 1.38). Conclusions Oral frailty has sustained adverse effects on mental well-being and is associated with an elevated risk of cognitive decline. Oral frailty may represent a potential target for interventions aimed at supporting mental and cognitive health in aging populations.