ECT is the application of a small amount of electricity (electro-) to the human brain to generate a brief grand-mal seizure (convulsive). The procedure (therapy) is done while the person is anesthetized and the muscles are relaxed.
ECT is the most effective treatment for biological depression and in many cases, the more severe the depression, the more likely it is that ECT will work. Response rates for an uncomplicated depression can be as high as 90%. For refractory depressions (those that haven’t responded to conventional medication treatment), the response rate is still in the 70-80% range in many studies. For depression where the diagnosis is less clear or particularly where there may be a combination of diagnoses, ECT may still be effective against depressive symptoms but the response rate is significantly lower (50-60%) and the response is often less satisfying to the patient. ECT has always been relatively safe. Now that the procedure has evolved (like most other treatments in medicine), we are able to administer the treatments in a way that is not particularly stressful for the patient, making it an increasingly sought after treatment.
It’s not clear ‘how’ ECT works exactly, but then it’s not clear how antidepressants work exactly either. We can measure neurochemical and physiological changes in the brain after a response to ECT, which are similar to the changes seen in patients who respond to antidepressant medications. Also, we know that some of the properties of the brain clearly change during ECT, suggesting physiological alterations and possibly system re-regulation. For example a person’s seizure threshold often rises over the course of treatment, requiring higher dosages of electricity to generate a seizure.
ECT does not cure Major Depressive Disorder (MDD) or Bipolar Disorder. It treats episodes of depression or mania. In other words, a response to ECT does not mean that the person will not get sick again in the future. Serious mood disorders are often relapsing disorders in most people and some preventive strategy is required even after a response to ECT (medicines or maintenance ECT are the two choices usually). It is useful to think about treatment as involving two goals: ‘getting well’ and ‘staying well’.