Pro/
antioxidant imbalance has been reported in
schizophrenia (SZ). However, the results of studies are inconsistent and usually do not include other factors that are highly affected by oxidative stress (OS).This cross-sectional study aimed to determine the serum levels of OS markers and their potential connection with
schizophrenia. The total sample comprised 147: 98 individuals with SZ -47 first-episode (FS) and 49 chronic patients (CS)-and 49 healthy individuals (HC) as a control group. The examination included clinical variables and serum levels of
antioxidants and oxidative damage products. The significant changes were observed in concentrations of all examined markers, without any specific direction of the pro/
antioxidant balance shift between SZ and HC. In the regression model adjusted for cofounders,
catalase: OR = 0.81 (95%CI: 0.74-0.88);
glutathione peroxidase: OR = 1.06 (95%CI: 1.02-1.10); total
antioxidant capacity: OR = 0.85 (95%CI: 0.75-0.98); oxidative stress index: OR = 1.25 (95%CI: 1.03-1.52); ferric reducing ability of plasma: OR = 0.79 (95%CI: 0.69-0.89);
advanced glycation end products: OR = 1.03 (95%CI: 1.01-1.04); and
advanced oxidation protein products (
AOPP): OR = 1.05 (95%CI: 1.03-1.07) turned out to be significant predictors of
schizophrenia. In the multiple stepwise regression model, pro/
antioxidant status and their interaction with the duration of illness-related factors affected
schizophrenia symptoms: positive symptoms (FRAPxKYN), negative (DITYR, FRAP, CAT), general (KYN), and over-all psychopathology (KYNxNFK). The results confirm differences in serum levels of oxidative
biomarkers between SZ patients and healthy individuals. The pro/
antioxidant status could be considered a predictor of
schizophrenia and the factor affects patients' symptom severity.