Association between the triglyceride-glucose index and the risk of post-stroke depression

Background Post-stroke depression (PSD) is a common complication after stroke that affects prognosis. The triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, is associated with cerebrovascular diseases, but its relationship with PSD remains unclear. This study investigated the association between TyG index and PSD risk in first-ever acute ischemic stroke (AIS) patients. Methods We enrolled 398 consecutive first-ever AIS patients and calculated baseline TyG index. PSD was assessed using the 17-item Hamilton Depression Rating Scale at 3 months post-stroke. Logistic regression, restricted cubic splines (RCS), and threshold effect models were used to evaluate the association and dose-response relationship. Results At 3 months, 126 patients (31.66%) developed PSD. The PSD group had significantly higher TyG index than the non-PSD group (9.03[8.34–9.34] vs. 8.56[8.17–9.05], P < 0.001). After adjusting for sex, NIHSS score, LDL-C, and HDL-C, TyG index remained independently associated with PSD (OR = 1.64, 95% CI: 1.28–2.09, P < 0.001). Patients in the highest TyG quartile had a significantly increased PSD risk compared with the lowest quartile (OR = 3.40, 95% CI:1.73–6.68, P < 0.001). RCS analysis revealed a non-linear relationship, with a turning point at 8.02 identified by threshold effect analysis; above this value, PSD risk increased significantly (OR = 1.97, 95% CI:1.43–2.72, P < 0.001). Subgroup analyses showed significant interactions in patients with diabetes (P for interaction = 0.046) and hyperlipidemia (P for interaction = 0.026). Conclusions Elevated TyG index is independently associated with increased PSD risk in a non-linear manner. A TyG index ≥ 8.02 may serve as a risk threshold for PSD, and this association appears more pronounced in patients with diabetes or hyperlipidemia.