Event-related potential correlates of ESS-C-defined relapse-risk status in clinically stable patients with schizophrenia: a cross-sectional study.

BACKGROUND: Schizophrenia (SCZ) is associated with a high relapse rate, but objective electrophysiological correlates of relapse-related clinical vulnerability remain insufficiently understood. Event-related potential (ERP) components, such as P3 and N2, have been widely investigated as markers of cognitive dysfunction in SCZ. However, relatively few studies have examined ERP characteristics in clinically stable patients stratified according to early warning signs of relapse. The present study investigated ERP characteristics in clinically stable patients with SCZ classified according to the Early Signs Scale-Chinese version (ESS-C), aiming to explore whether ERP components are associated with ESS-C-defined relapse-risk status. METHODS: A cross-sectional study design was adopted. A total of 70 patients with SCZ and 35 healthy controls (HCs) were initially recruited. After electroencephalography (EEG) preprocessing, 90 participants were included in the final analysis, comprising 30 HCs, 30 patients in the non-relapse-risk group (NR), and 30 patients in the relapse-risk group (RR). Patients with SCZ were classified into the NR and RR groups according to the ESS-C cutoff. ERP data were recorded using a three-stimulus visual oddball paradigm. The amplitudes and latencies of N2 at Cz and P3 at CPz were extracted, and their associations with negative symptoms were analyzed. RESULTS: A significant overall group effect was observed for P3 amplitude (F = 9.914, P < 0.001), with Bonferroni-corrected post hoc comparisons showing significantly higher P3 amplitude in the RR group than in the HC group (P < 0.001), while the NR group showed intermediate values. Sensitivity analysis restricted to patients with SCZ showed that ESS-C-defined relapse-risk status was significantly associated with P3 amplitude after adjustment for available clinical variables. N2 amplitude was positively correlated with negative symptom severity (r = 0.278, P < 0.05). CONCLUSIONS: Clinically stable patients with SCZ still exhibit abnormal neural information processing. P3 amplitude may be associated with ESS-C-defined relapse-risk status in clinically stable SCZ, whereas N2 may be related to negative symptom severity. These findings provide preliminary evidence that ERP components may be associated with relapse-risk status in clinically stable SCZ. CLINICAL TRIAL NUMBER: NA.