BDNF blood levels after electroconvulsive therapy in patients with mood disorders: a systematic review and meta-analysis.

Objectives: To evaluate whether electroconvulsive therapy (ECT), a very effective non-pharmacological treatment for mood disorders, induces neurotrophic effects, indexed by the measurement of peripheral brain-derived neurotrophic factor (BDNF) levels.

Methods: Systematic review and meta-analysis of clinical trials published in PubMed/Medline from the first date available to October 2013. We included studies measuring pre- and post-BDNF blood levels under ECT in patients with mood disorders in the acute depressive episode.

Results: Eleven studies (n = 221 subjects) were eligible. These studies enrolled subjects with unipolar, bipolar and psychotic depression and varied regarding electrode placement (unipolar vs. bipolar) and previous use of pharmacotherapy. Nonetheless, BDNF significantly increased after ECT (Hedges' g pooled, random-effects model of 0.354; 95% CI = 0.162-0.546). The results were robust according to sensitivity analysis and Begg's funnel plot did not suggest publication bias. Meta-regression results did not show association of the outcome with any clinical and demographic variable, including depression improvement.

Conclusions: Our meta-analysis indicates that, similar to pharmacological interventions, peripheral BDNF increases after ECT treatment. The lack of correlation between BDNF increasing and depression improvement suggests that ECT induces neurotrophic effects regardless of clinical response in depression.