Abnormal plasma oxidative stress markers in first-episode schizophrenia and associations with clinical symptoms and cognitive function.

Accumulating evidence suggests that oxidative stress (OS) contributes to the onset and progression of schizophrenia (SCZ). However, the pattern of OS alterations in first-episode, drug-naïve patients and their associations with clinical and cognitive features remain unclear. In this study, 98 first-episode SCZ patients and 96 matched healthy controls were recruited. Plasma levels of total antioxidant capacity (TAC), malondialdehyde (MDA), lipid peroxidation (LPO), NADPH oxidase (NOX), glutathione S-transferase (GST), and glutathione reductase (GR) were measured. Clinical symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS), and cognitive performance was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Compared with controls, patients exhibited significantly higher TAC, MDA, and LPO levels but lower NOX levels, while GST and GR showed no significant differences. RBANS total and subscale scores were markedly reduced in patients, indicating generalized cognitive impairment. Correlation analyses revealed that GST was positively correlated with total PANSS scores, GR with negative symptoms, and LPO with overall cognition, attention, and delayed recall. These findings indicate that first-episode SCZ patients display an imbalance between oxidative and antioxidant systems, and specific OS markers are linked to symptom severity and cognitive dysfunction. OS alterations may serve as potential early biomarkers and therapeutic targets for schizophrenia.