BDNF and major depressive disorder: This view is in line with a recent study in MDD patients undergoing ECT, showing that the increase in peripheral BDNF levels is positively correlated to both seizure quality markers as well as the interval between the last ECT session and the blood withdrawal.58 The authors suggested that this might be due to a delayed (>6 days) and increased equilibrium of peripheral BDNF that is secondary to an early central rise of the neurotrophin.