A defect in the antioxidant defense system in schizophrenia.

OBJECTIVES Several oxidants and antioxidants have been evaluated in schizophrenia. However, previous studies frequently focused on individual parameters. Determination of the total oxidant and antioxidant status may be more useful. Therefore, we aimed to evaluate both plasma total oxidant status (TOS) and total antioxidant status (TAS) together with the oxidative stress index (OSI) in schizophrenia patients for the first time in the literature. METHODS A total of 60 schizophrenia patients and 40 healthy volunteers were included in the study. The Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression-severity scale (CGI-S) were used to evaluate the severity of schizophrenia in the patients. TOS and TAS were measured in plasma and the OSI was calculated for patients and controls. RESULTS There was no difference between patients and controls with regard to TOS, but the patients' TAS and OSI were significantly lower and higher, respectively, than those of the controls. No difference was detected between the schizophrenia subtypes or between the patients on typical or atypical antipsychotic medications or a combination of the two with regard to oxidative parameters. There was a weak to moderately significant negative correlation between TAS and total, positive and general psychopathology PANSS scores. Finally, we found a weak to moderately significant negative correlation between the CGI-S score and TOS and between the CGI-S score and TAS. CONCLUSIONS There is a defect in the antioxidant defense system in schizophrenia. Known oxidative stress that causes oxidative cell damage and thus contributes to the pathophysiology of schizophrenia may be mainly related to this defensive defect.