Dissociative changes in gray matter volume following electroconvulsive therapy in major depressive disorder: a longitudinal structural magnetic resonance imaging study

Electroconvulsive therapy (ECT), has become a widely applied potent treatment in clinical practice for major depressive disorder (MDD) over decades. However, due to its nonspecific and spatially unfocused nature, the underlying mechanisms of ECT remain unclear. In this longitudinal study, 11 patients with MDD underwent magnetic resonance imaging (MRI) before and after ECT at three different time points. A longitudinal voxel-based morphology approach was performed to characterize dynamic changes in brain gray matter volume (GMV). Twelve age- and sex-matched healthy controls were recruited to identify structural brain changes of patients with MDD before and after ECT. The brain GMV was globally found to increase shortly after a series of ECT, and then decrease 1 month after ECT treatment exposure. This fluctuating tendency was localized to the bilateral inferior parietal lobes, bilateral insula, and right superior temporal cortex. After the global GMV was corrected, there were only significant global effect increases in GMV in the left anterior hippocampus and right caudate, which were both significantly correlated with the improvement of depression symptoms. However, 1 month after ECT treatments, there was still significantly reduced GMV following patients with MDD compared to healthy controls in the left putamen, right anterior cingulate, and left inferior temporal cortex, which was observed before ECT. These findings indicate that ECT in patients with MDD is closely associated with dissociative structural changes. The locally enhanced GMV in limbic areas may reflect that the ECT-related brain compensatory mechanisms contribute to brain structure recovery in MDD. Keywords