Association between triglyceride-glucose index and depression and the mediating role of hypertension: a cross-sectional study of obese adults

BACKGROUND: Recent findings indicate a positive correlation between the TyG (triglyceride-glucose) index and the incidence of depression. However, there is a notable lack of research addressing the relationship between the TyG index and depression in the obese population, which warrants focused investigation. METHODS: We conducted a cross-sectional study utilizing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2011 to 2018, focusing on obese adults aged 18 years and older. Our analysis employed various methodologies, including multivariate logistic regression, restricted cubic splines, subgroup analyses, mediation effect analysis, and machine learning techniques. RESULTS: A total of 3485 participants were included in the study, among whom 421 were diagnosed with depression, resulting in a prevalence rate of 12.1 %. After fully adjusting for relevant covariates, a positive association was found between the TyG index and depression [OR (95 % CI): 1.30 (1.09, 1.56), p < 0.005]. Restricted cubic spline analysis further corroborated this positive relationship. Additionally, machine learning techniques revealed that the TyG index is of considerable importance in relation to depression. Subsequent subgroup analyses demonstrated a significant interaction based on marital status and the presence of hypertension, with p < 0.05. Finally, mediation analysis indicated that hypertension serves as a mediator in the relationship between the TyG index and depression, with this mediating effect accounting for 10.04 % of the total effect, suggesting a positive facilitative role. CONCLUSION: This study found a positive association between the TyG index and the prevalence of depression among obese adults in the United States, with hypertension partially mediating this relationship.