Another important ECT neuroimaging study was published yesterday by the UCLA group headed by Katherine Narr and Randall Espinoza:

Hippocampal subregions and networks linked with antidepressant response to electroconvulsive therapy.

Leaver AM, et al. Mol Psychiatry 2020. PMID 32029885
Below is the url for the pdf:
https://drive.google.com/file/d/124QDYiUbvoqBVUkQNwTk5RkhMZqFnNIj/view?usp=sharing

44 patients with either unipolar or bipolar depression underwent a course of mostly right unilateral ECT. 36 healthy controls served as comparators. Participants received multimodal MRI, cognitive testing and depression ratings at four time points:
1) baseline, 2) before the 3rd ECT, 3) after the index course of ECT, and 4) 6 months after ECT. 
The main findings were:
 -responders showed increased CBF (cerebral blood flow) in right middle and left posterior hippocampus
-nonresponders showed increased CBF in bilateral anterior hippocampus 
 -responders showed increased GMV (gray matter volume) in right anterior hippocampus only
-non responders showed  increased GMV throughout bilateral hippocampus and surrounding tissue 
-functional connectivity within a hippocampus-thalamus-striatum network decreased only in responders after two treatments and after index
- increased hippocampal volume after ECT correlated with improved delayed recall of words after treatment

The authors concluded: "In sum, our results suggest that the location of ECT-related plasticity within the hippocampus may differ according to antidepressant outcome, and that larger amounts of hippocampal plasticity may not be conducive to positive antidepressant response."

This is obviously a very complex study, the findings are preliminary, and will require replication. While the efficacy findings take center stage, the cognitive findings are equally interesting, and contradict other recent data (ref #53: van Oostrom et al. J ECT. 2018; 34:117-23). The dissociation between brain changes associated with efficacy versus those associated with side effects is also fascinating.
I am optimistic that this line of neuroimaging research will ultimately elucidate the mechanism(s) of action of ECT and lead to better understanding of the etiology of psychiatric illness.







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