Brain Tissue Properties and ECT: It's Not Edema
Out on Pubmed, from researchers in several European countries, is this paper:
Temporal trajectory of brain tissue property changes induced by electroconvulsive therapy.
The abstract is copied below:
Background: After more than eight decades of electroconvulsive therapy (ECT) for pharmaco-resistant depression, the mechanisms governing its anti-depressant effects remain poorly understood. Computational anatomy studies using longitudinal T1-weighted magnetic resonance imaging (MRI) data have demonstrated ECT effects on hippocampus volume and cortical thickness, but they lack the interpretational specificity about underlying neurobiological processes.
Methods: We sought to fill in the gap of knowledge by acquiring quantitative MRI indicative for brain's myelin, iron and tissue water content at multiple time-points before, during and after ECT treatment. We adapted established tools for longitudinal spatial registration of MRI data to the relaxometry-based multi-parameter maps aiming to preserve the initial total signal amount and introduced a dedicated multivariate analytical framework.
Results: The whole-brain voxel-based analysis based on a multivariate general linear model showed that there is no brain tissue oedema contributing to the predicted ECT-induced hippocampus volume increase neither in the short, nor in the long-term observations. Improvements in depression symptom severity over time were associated with changes in both volume estimates and brain tissue properties expanding beyond mesial temporal lobe structures to anterior cingulate cortex, precuneus and striatum.
Conclusion: The obtained results stemming from multi-contrast MRI quantitative data provided a fingerprint of ECT-induced brain tissue changes over time that are contrasted against the background of established morphometry findings. The introduced data processing and statistical testing algorithms provided a reliable analytical framework for longitudinal multi-parameter brain maps. The results, particularly the evidence of lack of ECT impact on brain tissue water, should be considered preliminary considering the small sample size of the study.
Keywords: Longitudinal MRI; electroconvulsive therapy; hippocampus; major depression; voxel-based morphometry; voxel-based quantification
The pdf is here.
and a figure:
This study applied quantitative MRI (qMRI) at 4 time points and novel data analytic methods in 9 patients. Yes, 9 patients. A very big paper with a tiny sample. The methods contain pages of mathematical formulae that require very a sophisticated educational background to comprehend. For a reader like me, I must trust the authors and reviewers of the paper, that it is not total gobbledygook. With that caveat, the simple result, that brain volume increases after ECT are not the result of edema, is pretty interesting, and if replicated, very important.
The anatomic localization of brain changes, with multiple areas (including limbic, ACC, precuneus, basal ganglia) involved is also interesting, and builds upon other recent neuroimaging ECT data.
If you have a PhD in physics or math, please read every word of this paper (~45 minutes) and report back. For others, I recommend looking at the pictures, turning the pages, and absorbing this preliminary finding that the regional brain volume changes associated with ECT do not appear to be due to edema.
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