Research

Electroconvulsive therapy (ECT) is a procedure, done under general anesthetic, in which small electric currents are passed through the brain, intentionally triggering a brief seizure. ECT seems to cause changes in brain chemistry that can quickly reverse symptoms of certain mental illnesses. One of the main mental illnesses ECT is focused on is depression.

ECT is effective for 50% of people with treatment-resistant major depressive disorder. Follow-up treatment is still poorly studied but and average of half the patients who respond to ECT relapse within 12 months. Aside from effects in the brain, the general physical risks of ECT are similar to those of brief general anaesthesia. Immediately following treatment, the most common adverse effects are confusion and memory loss. ECT is considered one of the least harmful treatment options available for severely depressed pregnant women.

A usual course of ECT involves multiple administrations, typically given two or three times per week until the patient is no longer suffering symptoms. ECT is administered under anesthetic with a muscle relaxant.Electroconvulsive therapy can differ in its application in three ways: electrode placement, frequency of treatments, and the electrical waveform of the stimulus. These three forms of application have significant differences in both adverse side effects and symptom remission. Placement can be bilateral, in which the electric current is passed across the whole brain, or unilateral, in which the current is passed across one hemisphere of the brain. Bilateral placement seems to have greater efficacy than unilateral, but also carries greater risk of memory loss. Unilateral is thought to cause fewer cognitive effects than bilateral but is considered less effective if the dose administered is close to the seizure threshold.In the USA most patients receive bilateral ECT.In the UK almost all patients receive bilateral ECT. After treatment, drug therapy is usually continued, and some patients receive maintenance ECT.

Whether psychiatric medications are terminated prior to treatment or maintained, varies. However, drugs that are known to cause toxicity in combination with ECT, such as lithium, are discontinued, and benzodiazepines, which increase seizure thresholds,are either discontinued, a benzodiazepine antagonist is administered at each ECT session, or the ECT treatment is adjusted accordingly.

The electrodes deliver an electrical stimulus. The stimulus levels recommended for ECT are in excess of an individual's seizure threshold: about one and a half times seizure threshold for bilateral ECT and up to 12 times for unilateral ECT. Below these levels treatment may not be effective in spite of a seizure, while doses massively above threshold level, especially with bilateral ECT, expose patients to the risk of more severe cognitive impairment without additional therapeutic gains. Seizure threshold is determined by trial and error ("dose titration"). Some psychiatrists use dose titration, some still use "fixed dose" (that is, all patients are given the same dose) and others compromise by roughly estimating a patient's threshold according to age and sex.Older men tend to have higher thresholds than younger women, but it is not a hard and fast rule, and other factors, for example drugs, affect seizure threshold.