Electroconvulsive Therapy For Depression - How It Works
Main Category: Depression
Also Included In: Psychology / Psychiatry
Article Date: 19 Mar 2012 - 18:00 PDT
Electroconvulsive therapy (ECT) works by altering how different parts of the brain involved in depression communicate with each other, Scottish researchers reported in the journal PNAS (Proceeding of the National Academy of Sciences). ECT has been an effective and controversial therapy for depression for over seven decades; doctors knew it would often work, but were never sure why.
For individuals with serious mood disorder, using ECT, which involves anesthetizing them and using an electric shock to induce a seizure, has been the most effective treatment available for a long time.
A team of doctors and scientists from the University of Aberdeen and the University of Dundee, both in Scotland, have demonstrated that ECT impacts on how parts of the brain communicate - parts involved in depression.
When a patient has depression, parts of the brain that control mood and those involved in concentration and thinking have an overactive connection - ETC "turns down" that connection. When the connection goes back to normal, the patient can start enjoying life and performing daily tasks again.
The authors detected a close association between reduced connectivity after ECT and a considerable improvement in depressive symptoms.
Professor Ian Reid and team used fMRI (functional magnetic resonance imaging) to scan the brains of nine patients; six male and three female. All of them had been diagnosed with severe clinical depression and were successfully treated with ECT - two sessions per week, an average total of 8 treatments. None of the patients had responded to chemical antidepressants. They were scanned before ECT was applied, and then again afterwards. They used a new and complex mathematical analysis to measure any changes in brain connectivity.
Co-author, Professor Schwarzbauer said:
"With this new method we were able to find out to what extent more than 25,000 different brain areas 'communicated' with each other and how the brain's internal communication patterns differed before and after ECT treatment in severely depressed patients."
Professor Reid said:
"ECT is a controversial treatment, and one prominent criticism has been that it is not understood how it works and what it does to the brain. However we believe we've solved a 70 year old therapeutic riddle because our study reveals that ECT affects the way different parts of the brain involved in depression connect with one another.
For all the debate surrounding ECT, it is one of the most effective treatments not just in psychiatry but in the whole of medicine, because 75% to 85% of patients recover from the symptoms. Over the last couple of years there has been an emerging new perspective on how depression affects the brain.
This theory has suggested a 'hyperconnection' between the areas of the brain involved in emotional processing and mood change and the parts of the brain involved in thinking and concentrating. Our key finding is that if you compare the connections in the brain before and after ECT, ECT reduces the connection strength between these same areas - it reduces this hyperconnectivity.
For the first time we can point to something that ECT does in the brain that makes sense in the context of what we think is wrong in people who are depressed. "As far as we know no-one has extended that 'connectivity' idea about depression into an arena where you can show a treatment clearly treating depression, changing brain connectivity.
And the change that we see in the brain connections after ECT reflects the change that we see in the symptom profile of patients who generally see a big improvement."
The team members say they want to continue following-up on their patients to determine whether the hyperconnectivity, and the subsequent depression that comes of it, returns. They also plan to compare their ECT findings with those produced in studies that looked at other depression treatments, such as antidepressant medications and psychotherapy.
Professor Reid said:
"Although ECT is extremely effective, it is only used on people who need treatment quickly: either people who are very severely depressed, who are at risk from taking their own life and who perhaps can't look after themselves - or patients who have not responded to other treatments. The treatment can also affect memory, though for most patients this is short-lived. We monitor the memory function of all our patients receiving ECT in Grampian, and we find that function returns to normal within a few months.
Given the impact of depression itself on memory, it is perhaps unsurprising that such a rapidly acting treatment has this effect: certainly, the patterns of brain changes we have observed are consistent with this. However if we understand more about how ECT works, we will be in a better position to replace it with something less invasive and more acceptable. At the moment only about 40% of people with depression get better with treatment from their GP.
Our findings may lead to new drug targets which match the effectiveness of ECT without an impact on memory."
Professor Schwarzbauer said:
"The new method we devised for analysing the brain's functional connectivity in depression could be applied to a wide range of other brain disorders such as schizophrenia, autism, or dementia, and may lead to a better understanding of the underlying disease mechanisms and the development of new diagnostic tools."
Written by Christian Nordvist