The mediating role of cognitive function in the association between tooth loss and depressive symptoms: a...

Depression is a significant health concern among the aging population, and prior research suggests edentulism as a risk factor for depression. However, the specific mechanisms linking edentulism and depression are not fully understood.

This study aimed to investigate the complex interrelationships between tooth loss, cognitive function, and depressive symptoms in middle-aged and older adults. We specifically sought to determine if cognitive function mediates the association between tooth loss and depression.

This study performed a secondary analysis of cross-sectional data from the 2018 wave of the China Health and Retirement Longitudinal Study (CHARLS), with a mean age of 60.8 years (47% women, 53% men). Depressive symptoms, the binary outcome variable, were assessed using the 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10). Tooth loss was measured by self-report and categorized as a binary variable (complete tooth loss vs. not). Cognitive function, encompassing orientation, memory, calculation, and visuospatial skills, served as the mediate variable. Causal mediation analysis was performed to estimate the mediating role of cognitive function.

The final analysis included 11,000 participants. Univariate analysis showed a significant association between tooth loss and depression, which remained significant across all three multivariate logistic regression models. Causal mediation analysis indicated that the average causal mediation effect (ACME) of global cognitive ability on the association between tooth loss and depression was 0.043 (95% CI: 0.037, 0.050). The average direct effect (ADE) of tooth loss on depression was 0.024 (95% CI: 0.001, 0.050). Global cognitive ability mediated 61.6% of the total effect (95% CI: 0.439, 0.987).

In this nationally representative cohort, complete tooth loss was associated with a higher prevalence of depression, with cognitive impairment accounting for a substantial proportion of this association. This is the first study to quantify the mediating role of cognition in this pathway.