Predicting individual responses to lithium with oxidative stress markers in drug-free bipolar disorder.

This is the first study to investigate the oxidative stress (OxS) levels in drug-free bipolar disorder (BD) patients and their association with lithium response. A total of 61 drug-free BD patients and 49 controls were included. Patients treated with lithium were followed-up for 6 weeks. The levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and malondialdehyde (MDA) were measured at baseline and at the end of the sixth week. Compared to controls, the SOD levels were lower, whereas the MDA were higher in the BD-depression (BD-D) group (both  < 0.001). GSH-Px levels were higher in both the BD-D and the BD-mania (BD-M) group (both  < 0.001). Both GSH-Px and MDA levels in the BD ( = 0.009,  < 0.001) and the BD-D subgroup ( = 0.006,  = 0.001) decreased significantly after the 6-week treatment with lithium. Interestingly, both GSH-Px and MDA levels decreased in responders ( = 0.03,  = 0.002) but not in the non-responders of BD-D (both p > 0.05). Moreover, the reduction in the MDA levels were associated with lithium response ( = 1.47, Wald statistic = 5.94,  = 0.015, odds ratio = 4.35, 95% confidence interval 1.33-14.20). Our study demonstrates an imbalance of OxS in drug-free BD, especially BD-D. Lithium reduces the GSH-Px and MDA levels in BD patients. The reduction in MDA levels may predict individual responsiveness to lithium.