Association Between A Body Shape Index and Depression: Evidence From NHANES 2005-2018 With Mediation Analysis of the Triglyceride-Glucose Index

Purpose Growing evidence suggests a bidirectional relationship between depression and obesity. This study examined the association between A Body Shape Index (ABSI) and depressive symptoms among U.S. adults and explored the mediating role of the triglyceride-glucose (TyG) index. Design Cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES, 2005-2018). Setting United States, utilizing NHANES data collected between 2005 and 2018. Participants 15200 non-institutionalized U.S. adults aged >=20 years with complete data on ABSI, depression (assessed by PHQ-9), and TyG index. Methods Multivariate logistic regression, smooth curve fitting, subgroup/interaction analysis, and sensitivity analyses assessed the ABSI-depression link. Mediation analysis quantified the TyG index’s role. Results After adjusting for potential confounders, a significant positive association was observed between ABSI and depressive symptoms. Participants in the highest ABSI quartile (Q4) had higher odds of depression compared to those in the lowest quartile (Q1). Subgroup and sensitivity analyses confirmed the robustness and independence of this association. Mediation analysis revealed that the TyG index partially mediated the relationship between ABSI and depression, with a mediation effect accounting for 5.31% of the total association. Conclusion This large cross-sectional study highlights a significant association between higher ABSI and depressive symptoms among U.S. adults. These findings highlight the need for further research to explore underlying mechanisms and potential clinical implications.