Hippocampal Microstructural Changes Following ECT in Severe Depression: New MRI Findings From France

 Out on PubMed, from authors in France, is this paper:

Hippocampal microstructural changes following electroconvulsive therapy in severe depression.

Le Berre A, Attali D, Uszynski I, Debacker C, Lui M, Charron S, Moyal M, Ramon F, Henensal A, Benzakoun J, Mekaoui L, Gorwood P, Poupon C, Cachia A, Oppenheim C, Plaze M.Mol Psychiatry. 2025 Apr 8. doi: 10.1038/s41380-025-03016-x. Online ahead of print.PMID: 40199994

The abstract is copied below:

Electroconvulsive therapy (ECT) induces hippocampal volume increases in depressed patients, potentially reflecting neuroplasticity. We hypothesized that Neurite Orientation Dispersion and Density Imaging (NODDI) could provide in vivo evidence of hippocampal neuroplasticity following ECT. This longitudinal study evaluated 43 depressed patients undergoing ECT and 24 controls. MRI and clinical assessments were performed at baseline (V1), after 5 sessions (V2), and post-treatment (V3). Evaluations included a 3 T MR-scan with 3DT1-weighted and multi-shell diffusion (b = 200/1500/2500 s/mm², 30/45/60directions) sequences. Q-ball, Diffusion Tensor, and NODDI models provided: axial diffusivity (AD), radial diffusivity (RD), mean diffusivity (MD), fractional anisotropy (FA), generalized FA (GFA), neurite density index (NDI), isotropic fraction (Fiso), and orientation dispersion index (ODI). FreeSurfer extracted whole hippocampal and subfield volumes from T1-weighted images. Longitudinal changes were assessed with linear mixed-effect models. 107 MRIs from patients and 24 MRIs from controls were analyzed. ECT induced significant bilateral hippocampal volume increases (p < 0.001). Group comparisons showed consistently higher FA, lower GFA and ODI in patients compared to controls at all time-points. Following ECT, significant diffusion changes included decreased hippocampal GFA, FA, AD, MD and Fiso, along with increased ODI and NDI. NDI and Fiso changes were localized to the dentate gyrus but not the hippocampal tail. ECT responders showed a significant right hippocampal volume increase at V2 compared to non-responders. After ECT, hippocampal volume increases are accompanied by bilateral changes in NODDI parameters, particularly in the dentate gyrus, consistent with hippocampal neuroplasticity.

The paper is here.

And from the text:

This is an exciting neuroimaging study, showing both a normalization of hippocampal microarchitecture with ECT, as well as a correlation with early hippocampal volume increase and antidepressant response. It is a thoughtfully written and well presented paper. Of course, the findings will need to be replicated.

Kudos to our French colleagues for this important contribution to the ECT mechanism-of-action literature.