ECT is a brief electrical shock applied to the head that results in seizure and convulsions. At one time, this procedure was used so indiscriminately that it fell into disfavor. However, currently, it is used therapeutically with some success, in patients suffering severe depression, schizophrenia or biopolar disorder. The patient is sedated and paralyzed to prevent him thrashing about and injuring himself during the convulsions. Patients often report considerable (though usually temporary) relief from symptoms. The mechanism whereby ECT produces these improvements is unknown.

ECT can also cause anterograde amnesia for the time of the treatment and retrograde amnesia for the hours leading up to the treatment.