Oral Function, Loneliness, Depression, and Social Participation Among Physically Disabled Middle-Aged and Older Adult Individuals: Insights from a Japanese Cross-Sectional Study.

Background/Objectives: In the context of an aging society, physical disability and its relationship with frailty is of growing concern. The aim of this study was to examine the associations between oral function, social participation, and loneliness among community-dwelling middle-aged and older adult physically disabled individuals. Methods: In this cross-sectional study, the participants were 140 individuals with certified physical disabilities living in the studied area. Demographic characteristics, outing activities, loneliness (Three-Item Loneliness (TIL) Scale), and frailty/ability to live independently (Kihon Checklist (KCL)) were assessed using a questionnaire survey. The participants were divided into two groups based on the presence or absence of oral dysfunction (OD), and statistical analyses were performed to compare the groups. Results: The group with OD had significantly higher TIL and KCL total scores and significantly lower mobility, confinement, cognitive function, greater levels of depression, and fewer outing activities (volunteering, movies, festivals, sports) compared to the group without OD. In a multivariate, age- and sex-adjusted binomial logistic regression analysis, outing activities (OR = 0.011, 95% CI: 0.000-0.529, p = 0.023) and loneliness (OR = 6.174, 95%CI: 1.292-29.502, p = 0.023) were identified as significant factors. Conclusions: An association was found between OD, loneliness, and social activities among middle-aged and older individuals with physical disabilities. The results suggest that future interventions should consider the relationship between oral function and factors such as depression, loneliness, social isolation, and social engagement as a means to mitigate frailty and other health and well-being concerns for physically disabled individuals.