The Effect of Tooth Loss on Depression and Anxiety Among Older Adults in China: The Mediating Role of Dietary Diversity

<b>Background/Objectives</b>: Oral and mental health represent significant public health challenges for the global elderly population. This study aims to explore the association between tooth loss and depression and anxiety symptoms in Chinese elderly individuals, and to assess whether dietary diversity plays a mediating role in this relationship. <b>Methods</b>: This cross-sectional study recruited 8413 participants of the 2018 CLHLS. Depression and anxiety symptoms were evaluated with CES-D-10 and GAD-7, respectively. Multivariate logistic regression analysis was used to assess the effect of tooth loss on depression and anxiety symptoms, with adjustment for potential confounding factors. A mediation analysis, based on the PROCESS macro version 4.1, was conducted to further determine whether dietary diversity showed a potential indirect association in this relationship. <b>Results</b>: The prevalences of depression and anxiety symptoms were 14.1% and 12.1%. Compared to older adults with 0-8 tooth loss, those with 9-19 tooth loss had higher odds of both depression and anxiety, with odds ratios of 1.388 (95% CI: 1.109-1.614, <i>p</i> = 0.002) and 1.248 (95% CI: 1.031-1.512, <i>p</i> = 0.023), respectively. Those with 20-27 tooth loss exhibited the highest odds of depression, but no statistically significant increase in anxiety. Complete tooth loss was not significantly associated with either depression or anxiety in the fully adjusted models. Subgroup analysis showed that the association between tooth loss and depression/anxiety symptoms was statistically significant among males, rural residents, those living with family, those with chronic disease, and those without dentures. Mediation analysis suggested that dietary diversity showed a significant indirect association between tooth loss and depression symptoms (β = -0.192, SE = 0.027, 95% CI: -0.245, -0.139, <i>p</i> < 0.001), while no significant mediating effect was observed for anxiety symptoms. <b>Conclusions</b>: Moderate-to-severe tooth loss correlates with a higher risk of depression and anxiety symptoms in Chinese elderly, with dietary diversity partially mediating the tooth loss and depression association. This finding highlights the need for integrated strategies that combine oral health care, nutritional support, and mental health interventions in the early and middle stages of oral function impairment to protect the mental health of the elderly and improve their quality of life.