The triglyceride-glucose index in relation to psychotic symptoms in adolescents with major depressive disorder

It is increasingly recognized that insulin resistance (IR) is associated with major depressive disorder(MDD) and a spectrum of psychotic symptoms. However, a paucity of data exists regarding the connection of IR with concurrent psychotic symptoms in adolescent MDD patients. Consequently, we aimed to examine the correlation of the triglyceride-glucose index (TyG), an alternative measure of IR, with psychotic symptoms among adolescents presenting with MDD.

The study included 1,556 adolescents aged 13-17 years with depressive disorders. Demographic data were collected, and psychotic symptoms were assessed through clinical interviews. Assessment of depressive and anxiety symptoms was conducted with the 17-item Hamilton Depression Rating Scale (HAMD-17) and the 14-item Hamilton Anxiety Rating Scale (HAMA). Levels of fasting blood glucose (FBG), triglycerides (TG), and other serum markers were determined. The relationship between the TyG index and psychotic symptoms was subsequently investigated by applying multivariable binary logistic regression, restricted cubic spline (RCS), and threshold effect analyses.

A total of 1,556 patients were included in this study, with 1,158 females (74.4%) and 398 males (25.6%). Among all participants, 402 (25.8%) exhibited psychotic symptoms. A positive association persisted between the TyG index and psychotic symptoms after comprehensive covariate adjustment, demonstrating a 98.2% increase in odds per 1-unit increment in the index (OR = 1.982; 95% CI: 1.499, 2.620). Compared to the reference tertile (T1), participants in the highest TyG tertile (T3) exhibited significantly greater odds of psychotic symptoms (OR = 2.138; 95% CI: 1.526, 2.994). Furthermore, multivariable RCS analysis established that this relationship was nonlinear in nature (p = 0.045). Subsequent analysis pinpointed a TyG index of 8.06 as a critical threshold, beyond which the risk of psychotic symptoms emerged as significant (OR = 1.618, 95% CI: 1.108-2.363).

Analysis of the dose-response relationship revealed a J-shaped curve linking the TyG index to psychotic symptoms among adolescents with MDD, characterized by a threshold value near 8.06.