The associations of systemic inflammation and insulin resistance-related indicators with psychopathology and BDNF in patients with chronic schizophrenia

Background The triglyceride-glucose (TyG) index and C-reactive protein-triglyceride-glucose index (CTI) are innovative indicators for assessing insulin resistance (IR) and inflammation, yet research on them in patients with schizophrenia remains limited. This study aimed to explore TyG index and CTI levels and their associations with psychopathology and brain-derived neurotrophic factor (BDNF) in patients with chronic schizophrenia (CS). Methods This cross-sectional study was conducted across one general hospital and two psychiatric hospitals in Anhui Province, China. Socio-demographic information and hematological parameters were collected from participants, and their psychiatric and depressive symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) and the Calgary Depression Scale for Schizophrenia (CDSS), respectively. Results A total of 324 patients with CS and 150 healthy controls (HCs) were enrolled in the study. Compared with HCs, patients had higher TyG index and CTI levels (all P < 0.001). Binary logistic regression analyses revealed that among patients, a high TyG index level was significantly associated with higher BDNF levels and lower negative factor scores of the PANSS, while a high CTI level was significantly associated with higher depression-hopelessness factor scores of the CDSS and lower negative factor scores of the PANSS (all P < 0.05). Conclusion Patients with CS had higher levels of TyG index and CTI, which were significantly associated with the severity of negative and depressive symptoms, as well as BDNF levels. It is suggested that the integration of the TyG index and CTI into clinical monitoring for patients with CS is necessary.