Although results concerning SOD in BD have been inconsistent (Andreazza et al., 2008; Brown et al., 2014), we found that SOD levels were lower in trBD (both manic and depressive episodes) than in healthy controls, but the levels did not change after 6 weeks of ECT, even in ECT responders, suggesting that they could be a trait rather than a state in trBD. Here, SOD1 is linked to major depressive disorder.