Alterations in Resting-State EEG Functional Connectivity in Patients with Major Depressive Disorder Receiving ECT: Systematic Review From Switzerland

 Out on PubMed, from authors in Switzerland, is this review:

Alterations in resting-state EEG functional connectivity in patients with major depressive disorder receiving electroconvulsive therapy: A systematic review.

Ulrich S, Schneider E, Deuring G, Erni S, Ridder M, Sarlon J, Brühl AB.Neurosci Biobehav Rev. 2025 Jan 17:106017. doi: 10.1016/j.neubiorev.2025.106017. Online ahead of print.PMID: 39828233

The abstract is copied below:

Electroconvulsive therapy (ECT) is highly efficacious for the treatment of major depressive disorder (MDD), but its mechanisms still require clarification. Even though depression is associated with alterations in functional connectivity (FC), EEG studies investigating effects of ECT on FC have not been systematically reviewed. Understanding these effects may help to identify the role of functional brain circuits in depression and its remission. This systematic review aimed to synthesize EEG studies investigating FC changes in ECT-treated patients with depression. A systematic literature search was conducted following PRISMA guidelines. Peer-reviewed studies on pre-to post-ECT resting-state EEG FC changes in adult patients with MDD were included. Three of 143 studies were included, of which two reported reduced FC in the alpha and beta frequency bands and increased theta band FC in patients with ECT-treated MDD. Changes in alpha band FC were associated with treatment outcomes. Patients with MDD exhibit increased electrophysiological resting-state alpha band FC, particularly frontally, compared with healthy subjects. Thus, ECT-induced decrease might indicate a trend toward normalization of oscillatory brain rhythms. As brain oscillations have been proposed to be involved in neuronal synchronization, which is important for communication between networks, the potential restoration in patients with depression and the association of FC changes with clinical improvement may indicate a potential mechanism of action of ECT. Understanding ECT's underlying mechanisms might ultimately enable treatment optimization, thus enhancing patient care. However, the number of studies is limited, with low-to-moderate EEG study quality, small sample sizes, and different electrophysiological FC measures.

Keywords: brain networks; electroconvulsive therapy; electroencephalography; functional connectivity; major depressive disorder; phase synchronization.

The article is here.

And from the text:

Here is one for EEG enthusiasts. This is a literature review of studies that used EEG (not fMRI) to investigate resting state functional connectivity in depressed patients. Turns out there are only ~3 such studies, with a total n=60.

This is fascinating stuff, but very preliminary and still highly speculative. I'm not sure how much this advances us beyond the observation that ECT increases delta activity in the EEG which is correlated with efficacy and decrements in the weeks following ECT...