Background Recent research suggests that the obesity-related triglyceride-glucose (TyG) index is associated with cognitive status and depressive symptoms. However, the existing evidence is limited and inconsistent. Furthermore, it remains unclear whether depressive symptoms play a significant role in the relationship between obesity-related TyG indexes and cognitive status. Objective This study aims to investigate the relationship among the obesity-related TyG index, cognitive status, and depressive symptoms, as well as the role of depressive symptoms in the association between obesity-related TyG indexes and cognitive status. Methods A total of 5,822 participants from the China Health and Retirement Longitudinal Study (CHARLS) were included in this study. Cognitive status was assessed using the Telephone Interview of Cognitive Status (TICS), while depressive symptoms were evaluated using the 10-item version of the Center for Epidemiologic Studies Depression Scale (CES-D-10). TyG and obesity-related indicators (body mass index BMI, waist circumference WC, and waist-to-height ratio WHtR) were calculated from individual blood and physical examinations. Multivariate linear regression was employed to examine the associations among the obesity-related TyG index, depressive symptoms, and cognitive status. Restricted cubic spline (RCS) analysis was used to test the non-linear relationships between the obesity-related TyG index and both cognitive status and depressive symptoms. Mediation analysis was conducted to assess the role of depressive symptoms in the relationship between the obesity-related TyG index and cognitive status. Results The TyG-BMI (coefficient: 0.206; 95% confidence interval CI : 0.069, 0.343), TyG-WC (0.268; 0.135, 0.402), and TyG-WHtR (0.150; 0.013, 0.286) were positively associated with cognitive status. In contrast, TyG-BMI (-0.147; -0.292, -0.002) and TyG-WC (-0.163; -0.306, -0.021) exhibited a negative relationship with depressive symptoms. RCS analysis indicated a non-linear relationship between TyG-BMI, TyG-WC, and TyG-WHtR and both cognitive status and depressive symptoms. Mediation analysis revealed that depressive symptoms played an important role in the associations between both TyG-BMI and TyG-WC and cognitive status, with mediation proportions of 6.8% and 5.8%, respectively. Conclusion Depressive symptoms plays an important role in the relationship between both TyG-BMI and TyG-WC and cognitive status, highlighting depressive symptoms as a potentially relevant pathway that warrants further longitudinal and interventional validation.
Jiang et al. (Tue,) studied this question.