Electroconvulsive therapy induces remodeling of hippocampal co-activation with the default mode network in patients with depression

• Published in: NeuroImage clinical 2023-01, Vol.38, p.103404-103404, Article 103404
• Main Authors: Denier, Niklaus, Walther, Sebastian, Breit, Sigrid, Mertse, Nicolas, Federspiel, Andrea, Meyer, Agnes, Soravia, Leila M., Wallimann, Meret, Wiest, Roland, Bracht, Tobias
• Format: Article
• Language: English
• Subjects: Default Mode Network; Depression - diagnostic imaging; Depression - therapy; ECT; Electroconvulsive Therapy; Hippocampus; Hippocampus - diagnostic imaging; Hippocampus - pathology; Humans; Magnetic Resonance Imaging; Regular; Resting state functional connectivity; Uncinate fasciculus, parahippocampal cingulum, posterior cingulate cortex; White matter
• ISSN: 2213-1582; 2213-1582
• DOI: 10.1016/j.nicl.2023.103404

•ECT modifies coupling between the hippocampus and the default mode network.•ECT induces microstructural alterations in the parahippocampal cingulum.•ECT reverses reductions in posterior cingulate cortex functional connectivity (FC)•ECT decreases FC between the hippocampus and the posterior cingulate cortex.•ECT increases FC between the hippocampus and the supplementary motor area. Electroconvulsive therapy (ECT) is a highly efficient treatment for depression. Previous studies repeatedly reported an ECT-induced volume increase in the hippocampi. We assume that this also affects extended hippocampal networks. This study aims to investigate the structural and functional interplay between hippocampi, hippocampal pathways and core regions of the default mode network (DMN). Twenty patients with a current depressive episode receiving ECT-treatment and twenty age and sex matched healthy controls (HC) were included in the study. ECT-patients underwent multimodal magnetic resonance imaging (MRI)-scans (diffusion weighted imaging, resting state functional MRI) before and after an ECT-index series. HC were also scanned twice in a similar between-scan time-interval. Parahippocampal cingulum (PHC) and uncinate fasciculus (UF) were reconstructed for each participant using manual tractography. Fractional anisotropy (FA) was averaged across tracts. Furthermore, we investigated seed-based functional connectivity (FC) from bilateral hippocampi and from the PCC, a core region of the DMN. At baseline, FA in PHC and UF did not differ between groups. There was no baseline group difference of hippocampal-FC. PCC-FC was decreased in ECT-patients. ECT induced a decrease in FA in the left PHC in the ECT group. No longitudinal changes of FA were found in the UF. Furthermore, there was a decrease in hippocampal-PCC-FC, an increase in hippocampal-supplementary motor area-FC, and an increase in PCC-FC in the ECT-group, reversing group differences at baseline. Our findings suggest that ECT induces structural and functional remodeling of a hippocampal-DMN. Those changes may contribute to ECT-induced clinical response in patients with depression.