Loneliness and Its Association with Depression, Aspiration Risk, and Conversation in Japanese Older Adults

Background/Objectives: Loneliness is a critical public health concern associated with adverse mental and physical health outcomes in later life. However, few large-scale studies have examined loneliness in relation to depression, aspiration risk, frailty, and social participation among Japanese older adults. This study examined associations between loneliness and psychosocial and health-related factors among older adults. Methods: This cross-sectional study involved a secondary analysis of data obtained from online surveys conducted in 2018 and 2021 among 1000 community-dwelling Japanese adults (≥65 years). Loneliness was assessed using the UCLA Loneliness Scale Version 3 and dichotomized at the median to define a high-loneliness group. Depressive symptoms, aspiration risk, frailty, conversation frequency, and volunteering participation were assessed using validated scales. Multivariable logistic regression was used to identify factors associated with loneliness and interaction terms were examined to assess effect modification. Results: High loneliness was observed in 52.2% of participants. Greater loneliness was significantly associated with depressive symptoms (GDS ≥ 5; OR = 4.69, 95% CI: 2.84–7.76), higher dysphagia risk (DRACE score; OR = 1.08, 95% CI: 1.00–1.16), and lower daily conversation frequency (OR = 0.76, 95% CI: 0.67–0.86); however, volunteering (OR = 0.475, 95% CI: 0.23–0.87) was a protective factor. Conclusions: Loneliness among Japanese older adults is closely linked to depressive symptoms and aspiration risk, while frequent conversations and volunteer participation appear to be protective. Community-based interventions promoting social engagement and oral health may mitigate loneliness and its health consequences and improve quality of life for older adults. Given the cross-sectional design, the observed associations should not be interpreted as causal.