Reduced antioxidant defense systems in schizophrenia and bipolar I disorder

Abstract Numerous evidence and proofs suggest that the oxidative stress contributes to the pathogenesis of schizophrenia (SZ) and bipolar disorder (BD). The aim of this study is to determine the glutathione levels and the antioxidant enzyme activities in blood samples of patients suffering from SZ and patients with bipolar disorder in comparison with the healthy controlled subjects. It was a case-controlled study carried on upon three groups: forty-six SZ patients (41 men and 5 women, mean age = 33.2 ± 7 years), thirty BD patients (25 men and 5 women, mean age = 31.3 ± 8 years) and forty healthy controls (33 men and 7 women, mean age = 32.3 ± 7 years). The glutathione levels are the total glutathione (GSHt), the reduced glutathione (GSHr), and the oxidized glutathione (GSSG) and the antioxidant enzyme activities that are the superoxide dismutase (SOD), the glutathione peroxidase (GPx), and the catalase (CAT) are determined by the spectrophotometer. We noticed that the GSHt and the GSHr levels significantly decreased in both SZ and BD patients in comparison with the healthy control subjects. As for SOD and CAT activities they remained lower for the patients with SZ when compared both with the controls or the BD patients. We noticed as well that the CAT activity was significantly lower in the BD group than that in the control group, whereas, GPx activity showed no significant change in each group. Hence, this report of the decreased plasma levels of GSHt and GSHr, and the impaired antioxidant enzyme activities in SZ and BD patients aims at highlighting the GSH deficit that seems to be contributing to these disorders, and showing that it may be an important indirect biomarker of the oxidative stress for the SZ and BD.