BDNF plasma levels and genotype in depression and the response to electroconvulsive therapy

Brain derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of depression and the antidepressant response. Electroconvulsive therapy (ECT) is reported to increase BDNF levels in blood, though only a small number of studies have been conducted to date. Our objectives were to: 1) compare plasma BDNF levels in medicated patients with depression and controls; 2) assess the effect of ECT on plasma BDNF levels in medicated patients with depression; 3) explore the relationship between plasma BDNF levels and the Val66Met (rs6265) BDNF polymorphism; and 4) examine the relationship between plasma BDNF levels and clinical symptoms and outcomes with ECT. Plasma BDNF levels were analyzed in samples from 61 medicated patients with a major depressive episode and 50 healthy controls, and in patient samples following a course of ECT. Fifty-two samples from the depressed patient group were genotyped for the Val66Met BDNF polymorphism. There was no difference in plasma BDNF levels between the control and depressed groups, and there was no difference in plasma BDNF levels in patients following treatment with ECT. In line with previous reports, we show that, in medicated patients with depression, Met-carriers had higher plasma BDNF levels than Val-carriers, though genotype was not related to clinical response. We found no association between plasma BDNF levels and depression severity or the clinical response to ECT. Our results suggest that plasma BDNF does not represent a suitable candidate biomarker for determining the therapeutic response to ECT. •Plasma BDNF levels do not differ between controls and patients with depression.•Plasma BDNF levels do not change following a course of ECT.•Patients with Val/Met or Met/Met genotype have higher BDNF levels than Val/Val.•Plasma BDNF levels are not related to depression symptom severity.•Plasma BDNF levels are not associated with the therapeutic response to ECT.