Meta-analysis of Brain Structural Changes After Electroconvulsive Therapy in Depression.
Out on PubMed, from researchers in Austria and Germany, is this paper:
Meta-analysis of brain structural changes after electroconvulsive therapy in depression.
Brain Stimul. 2021 Jun 10:S1935-861X(21)00114-5. doi: 10.1016/j.brs.2021.05.014. Online ahead of print.PMID: 34119669
The abstract is copied below:
Background: Increases in the volume of the amygdala and hippocampus after electroconvulsive therapy (ECT) are among the most robust effects known to the brain-imaging field. Recent advances in the segmentation of substructures of these regions allow for novel insights on the relationship between brain structure and clinical outcomes of ECT.
Objective: We aimed to provide a comprehensive synthesis of evidence available on changes in brain structure after ECT, including recently published data on hippocampal subfields.
Methods: A meta-analysis of published studies was carried out using random-effects models of standardized mean change of regional brain volumes measured with longitudinal magnetic resonance imaging of depressive patients before and after a series of ECT treatments.
Results: Data from 21 studies (543 depressed patients) was analysed, including 6 studies (118 patients) on hippocampal subfields. Meta-analyses could be carried out for seven brain regions for which data from at least three published studies was available. We observed increases in left and right hippocampi, amygdalae, cornua ammonis (CA) 1, CA 2/3, dentate gyri (DG) and subicula with standardized mean change scores ranging between 0.34 and 1.15. The model did not reveal significant volume increases in the caudate. Meta-regression indicated a negative relationship between the reported increases in the DG and relative symptom improvement (-0.27 (SE: 0.09) per 10%).
Conclusions: ECT is accompanied by significant volume increases in the bilateral hippocampus and amygdala that are not associated with treatment outcome. Among hippocampal subfields, the most robust volume increases after ECT were measured in the dentate gyrus. The indicated negative correlation of this effect with antidepressant efficacy warrants replication in data of individual patients.
Keywords: Dentate gyrus; Electroconvulsive therapy; Hippocampal subfields; Hippocampus; Meta-analysis; Volume.
and from the text:
This meta-analysis of ECT-induced volumetric changes includes data of 543 depressed subjects published in 21 studies and provides convincing evidence for significant volume enlargements in all seven assessed brain regions after a full ECT course. This is the first meta-analysis that includes the caudate and in particular most recent findings regarding hippocampal subfields. Previous meta-analyses focused on the hippocampus.
While it is generally assumed that ECT-induced structural changes are the result of neuroplasticity rather than unspecific tissue reactions to electrical current [27] or edema [49,50], longitudinal studies assessing in vivo brain plasticity in ECT-treated patients are lacking. As yet, we have not identified the molecular processes on the basis of the volumetric changes observed after ECT, nor can we say with certainty whether they bear a clinical relevance or rather constitute an epiphenomenon of the electrical stimulation of the brain.
To sum up, we provide the most up-to-date and largest meta-analysis of ECT-induced structural changes and our results clearly support the notion of ECT-induced volume enlargements in the hippocampus including its subfields, the amygdala and the caudate nucleus. The extent of these structural increments within the hippocampus seems to be influenced by age. The DG seems to be the most promising region in terms of facilitating outcome predictions for future investigations. We observed a negative correlation between volumetric changes in the left DG and antidepressant efficacy that warrants replication in future large-scale investigations.
ECT neuroimaging data continue to appear in the literature at a rapid rate; this meta-analysis is a natural spin-off of that. Complex imaging and statistical techniques lead to clear and compelling findings of regional brain structural volume increase. As yet, the exact cellular etiology of the volume changes and correlations with clinical outcome are unknown.
The discussion section of this paper is worth reading for its excellent review of possible mechanisms for the observed changes.
All followers of the neuroimaging literature will want to read this paper in full, ~25 minutes.
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