ECT is an uncommon
treatment for severe, chronic depression. It is used sparingly, partially
because our understanding of why and how it works is still in the dark ages. It
also doesn’t help that it can cause memory loss in many patients who undergo it
(usually confined to just memory around ECT treatments, but occasionally also
around older, longer-term memories as well), as well as increasing attention
and concentration problems in a minority of people who try ECT.
However, a new study sheds light on the possible
mechanism for how electroconvulsive therapy works, based upon one theory of how
depression works in the brain.
The theory goes like this — depression isn’t caused by
too little brain activity. It’s actually caused by too much brain activity, an
overactive brain that has accidentally “hot-wired” multiple brain networks
together. (How and why this hot-wiring occurs is still a mystery.)
So how can ECT undo this hot-wiring?
It’s theorized that ECT may undo this hot-wiring, and
return the brain’s neural networks to normal functioning:
In a study led by psychiatrist Ian Reid of Aberdeen,
Schwarzbauer and colleagues performed functional magnetic resonance imaging
(fMRI) scans of nine depressed patients before and after ECT. Rather than
focusing on activity in previously suspected brain areas, the researchers
examined connectivity in the brain as a whole, examining changes in blood
oxygenation in about 27,000 points known as voxels (the 3D imaging equivalent
of pixels on a computer screen).
After treatment with ECT, connectivity was dramatically
decreased in one cluster of voxels around an area called the dorsolateral
prefrontal cortex, the researchers report today in the Proceedings of the
National Academy of Sciences. Decreases in connectivity reflected improvements
in symptoms, as reported by the patients.
This finding indicates that ECT reduces the influence of
the dorsolateral prefrontal cortex on this nexus.
Granted, this is a tiny study done on just 9 patients, so
we really can’t generalize these findings to a broader population at this time
until the findings are properly replicated by other researchers.
Still, it’s an interesting preliminary finding that may
explain why ECT can be effective. It fails to explain, however, why
antidepressants work (assuming, logically, that most depression functions
through similar brain mechanisms).
Image source: http://www.sxc.hu/photo/1043923
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