Electroconvulsive Therapy For Depression - How It Works

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.