Oxidative Stress Parameters in Recent-Onset Bipolar Disorder and Possible Lithium Antioxidant Effect

Abstract

Background: Several studies have shown oxidative stress (OxS) and imbalance of antioxidant enzymes in bipolar disorder (BD). Lithium is a gold-standard treatment in BD and showed a role in decreasing OxS. Despite few data available for recent-onset BD, increased antioxidant defenses were found in first episode of bipolar mania. No study, however, evaluated OxS parameters in depression of recent-onset BD and the effects of lithium treatment in OxS in bipolar depression. Methods: BD subjects in a depressive episode (n=25) with no more than 5 years of illness duration were enrolled and treated for 6 weeks with lithium monotherapy, although hypnotics use as needed was allowed. Blood samples were collected at baseline and after 6-week lithium treatment. Healthy controls (n=28) were used for comparison with patients. Tiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were measured spectrophotometrically. Results: BD patients had increased CAT (ANCOVA, df=1, 47, F=56.60, p<0.001), enhanced GPx (ANCOVA, df=1, 49, F=12.20, p=0.001) and decreased SOD/CAT ratio (ANCOVA, df=1, 44, F=30.66, p<0.001) compared to healthy controls. Also, no differences in SOD or TBARS between subjects with BD and healthy controls was observed. Regarding lithium treatment effects, BD patients had a decrease in TBARS (Wilcoxon Signed Ranks Test, z=-2.81, p=0.005) levels, with no changes in other parameters. Conclusions: Results suggest that recent-onset BD may have enhanced antioxidant enzymes. Lithium showed efficacy against OxS, confirming its neuroprotective role.