Acute and subsequent continuation electroconvulsive therapy elevates serum BDNF levels in patients with major depression

Introduction: The induction of brain-derived neurotrophic factor (BDNF) release and subsequent restoration of neuroplastic homeostasis may underlie the effects of electroconvulsive therapy (ECT). Objectives: We aimed to assess serum and plasma BDNF levels during the course of acute ECT, as well as before and after subsequent continuation ECT, in patients with depression. Methods: We included 24 patients with major depressive disorder (mean age ± SD: 54.5 ± 13.7; f/m: 17/7; baseline 17-item Hamilton Depression Rating Scale score of 26.79 ± 4.01). Serum and plasma BDNF (sBDNF, pBDNF) levels were assessed at nine time-points before, during, and after acute ECT series. Data were analysed using linear regression and linear mixed models, which were adjusted for multiple comparisons via Bonferroni correction. Five patients received continuation ECT subsequent to the acute ECT series. In these patients, BDNF levels were assessed before and after each two continuation ECT sessions using Wilcoxon signed-rank tests. Results: Relative to baseline (mean ng/ml ±SD: 24.68 ± 14.40), sBDNF levels were significantly higher 1 day (33.04 ± 14.11, p = 0.013, corrected), 1 week (37.03 ± 10.29, p < 0.001, corrected), and 1 month (41.05 ± 10.67, p = 0.008, corrected) after the final ECT session, while pBDNF levels did not significantly differ (p > 0.1). Furthermore, our results indicated that sBDNF levels increased after each continuation ECT session. There was no significant association between sBDNF levels and clinical parameters or treatment response. Conclusion: The absence of an association between changes in sBDNF levels and depressive symptoms challenges the proposed concept of sBDNF/pBDNF as key markers of the effects of ECT.