A meta-analysis of oxidative stress markers in schizophrenia

Oxidative stress has been identified as a possible element in the neuropathological processes of schizophrenia (SCZ). Alteration of oxidative stress markers has been reported in SCZ studies, but with inconsistent results. To evaluate the risk of oxidative stress to schizophrenia, a meta analysis was conducted, including five markers of oxidative stress [thiobarbituric reactive substances (TBARS), nitric oxide (NO), catalase (CAT), glutathione peroxidase (GP) and superoxide dismutase (SOD)] in SCZ patients versus healthy controls. This study showed that TBARS and NO significantly increased in SCZ, while SOD activity significantly decreased in the disorganized type of SCZ patients. No significant effect size was found for the activities of GP and CAT in SCZ patients (P>0.05). Egger's regression test observed no significant publication bias across the oxidative stress markers, but found high heterogeneities in all the 5 markers. The subgroup analysis suggested that the ethnicity, sample size of patients and sample sources may contribute to the heterogeneity of the results for TBARS, NO and SOD. The result further demonstrated the involvement of oxidative stress in the pathophysiology of schizophrenia.