Changes in interleukin-6 levels during electroconvulsive therapy may reflect the therapeutic response in major depression

Objective: Interleukin-6 (IL-6) has been reported to be elevated in major depressive disorder (MDD) but decreased by antidepressive medication. IL-6 levels are markedly elevated both after epileptic seizures and single electroconvulsive therapy (ECT) session, but long-term changes in IL-6 levels after ECT have not been studied. The correlation between immediate and long-term changes in proinflammatory cytokines and outcome after ECT was investigated. Method: Thirty patients suffering from MDD participated in the study. IL-6, interleukin-1b (IL-1b) and interleukin-1 receptor antagonist (IL-1RA) levels were examined at baseline and at 2 and 4 h after the first, fifth and the last ECT sessions. The response to ECT was measured with Montgomery-Asberg Depression Rating Scale (MADRS). Results: ECT repeatedly caused an increase in IL-6 levels at the 4-h time point. However, the baseline IL-6 levels decreased among remitters, but not among non-remitters, towards the end of ECT. IL-1b levels were mostly below detectable level, and IL-1Ra levels did not change during and after ECT. Conclusion: ECT has distinct acute and long-term effects on IL-6 levels. Interestingly, the long-term effect of ECT on IL-6 seems to correlate with outcome, providing further evidence of the mechanism of action of ECT and supporting the inflammation theory in MDD.