Electroconvulsive therapy (ECT), formerly known as electroshock therapy, is a psychiatric treatment in which seizures in the brain (without muscular convulsions) are electrically induced in patients to provide relief from mental disorders. Typically, 70 to 120 volts are applied externally to the patient's head resulting in approximately 800 milliamperes of direct current passed through the brain, for 100 milliseconds to 6 seconds duration, either from temple to temple (bilateral ECT) or from front to back of one side of the head (unilateral ECT).
The ECT procedure was first conducted in 1938 by Italian psychiatrist Ugo Cerletti and rapidly replaced less safe and effective forms of biological treatments in use at the time. ECT is often used with informed consent as a safe and effective intervention for major depressive disorder, mania, and catatonia. ECT machines were originally placed in the Class III category by the United States Food and Drug Administration (FDA) in 1976. They were re-classified as Class II devices, for treatment of catatonia, major depressive disorder, and bipolar disorder, in 2018.A course of ECT is effective for about 50% of people with treatment-resistant major depressive disorder, whether it is unipolar or bipolar. Follow-up treatment is still poorly studied, but about half of people who respond relapse within 12 months. Aside from effects in the brain, the general physical risks of ECT are similar to those of brief general anesthesia. Immediately following treatment, the most common adverse effects are confusion and transient memory loss. Among treatments for severely depressed pregnant women, ECT is one of the least harmful to the gestating fetus.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 anesthesia with a muscle relaxant. ECT can differ in its application in three ways: electrode placement, treatment frequency, and the electrical waveform of the stimulus. These treatment parameters can pose significant differences in both adverse side effects and symptom remission in the treated patient.
Placement can be bilateral, where the electric current is passed from one side of the brain to the other, or unilateral, in which the current is solely passed across one hemisphere of the brain. Bilateral electrode placement seems to have greater effectiveness than unilateral electrode placement, but also carries a higher risk of memory loss. After treatment, drug therapy is usually continued and some patients will continue to receive maintenance ECT treatments.ECT appears to work in the short term via an anticonvulsant effect primarily in the frontal lobes and longer term via neurotrophic effects primarily in the medial temporal lobe.