37% relapsing within the first 6 months. about twice as many relapsed with no antidepressants. most of the evidence for continuation therapy is with tricyclic antidepressants; evidence for relapse prevention with newer antidepressants is lacking. lithium has also been found to reduce the risk of relapse; especially in younger patients. catatonia ect is generally a second-line treatment for people with catatonia who do not respond to other treatments, but is a first-line treatment for severe or life-threatening catatonia. there is a plethora of evidence for its efficacy, notwithstanding a lack of randomised controlled trials, such that "the excellent efficacy of ect in catatonia is generally acknowledged". for people with autism spectrum disorders who have catatonia, there is little published evidence about the efficacy of ect; as of 2014 there were twelve case reports. mania ect is used to treat people who have severe or prolonged mania; nice recommends it only in life-threatening situations or when other treatments have failed and as a second-line treatment for bipolar mania. schizophrenia ect is widely used worldwide in the treatment of schizophrenia, but in north america and western europe it is invariably used only in treatment resistant schizophrenia when symptoms show little response to antipsychotics; there is comprehensive research evidence for such practice. it is useful in the case of severe exacerbations of catatonic schizophrenia, whether excited or stuporous. there are also case reports of ect improving persistent psychotic symptoms associated with stimulant-induced psychosis. effects aside from effects in the brain, the general physical risks of ect are similar to those of brief general anesthesia; the us surgeon general's report says that there are "no absolute health contraindications" to its use.: 259 immediately following treatment, the most common adverse effects are confusion and memory loss. some patients experience muscle soreness after ect. there is evidence and rationale to support giving low doses of benzodiazepines or otherwise low doses of general anesthetics, which induce sedation but not anesthesia, to patients to reduce adverse effects of ect. while there are no absolute contraindications for ect, there is increased risk for patients who have unstable or severe cardiovascular conditions or aneurysms; who have recently had a stroke; who have increased intracranial pressure (for instance, due to a solid brain tumor), or who have severe pulmonary conditions, or who are generally at high risk for receiving anesthesia.: 30 in adolescents, ect is highly efficient for several psychiatric disorders, with few and relatively benign adverse effects. risk of death a meta-analysis from 2017 found that the death rate of ect was around 2.1 per 100,000 procedures. a review from 2011 reported an estimate of the mortality rate associated with ect as less than 1 death per 73,440 treatments. cognitive impairment cognitive impairment is sometimes noticed after ect. the american psychiatric association (apa) report in 2001 acknowledges: "in some patients the recovery from retrograde amnesia will be incomplete, and evidence has shown that ect can result in persistent or permanent memory loss". after treatment, drug therapy is usually continued and some patients will continue to receive maintenance ect treatments. it is the purported effects of ect on long-term memory that give rise to much of the concern surrounding its use. however, the methods used to measure memory loss are generally poor, and their application to people with depression, who have cognitive deficits including problems with memory, have been problematic. the acute effects of ect can include amnesia, both retrograde (for events occurring before the treatment) and anterograde (for events occurring after the treatment). memory loss and confusion are more pronounced with bilateral electrode placement rather than unilateral, and with outdated sine-wave rather than brief-pulse currents. the use of either constant or pulsing electrical impulses also varied the memory loss results in patients. patients who received pulsing electrical impulses, as opposed to a steady flow, seemed to incur less memory loss. the vast majority of modern treatment uses brief pulse currents. retrograde amnesia is most marked for events occurring in the weeks or months before treatment, with one study showing that although some people lose memories from years prior to treatment, recovery of such memories was "virtually complete" by seven months post-treatment, with the only enduring loss being memories in the weeks and months prior to the treatment. anterograde memory loss is usually limited to the time of treatment itself or shortly afterwards. in the weeks and months following ect these memory problems gradually improve, but some people have persistent losses, especially with bilateral ect. one published review summarizing the results of questionnaires about subjective memory loss found that between 29% and 55% of respondents believed they experienced long-lasting or permanent memory changes. in 2000, american psychiatrist sarah lisanby and colleagues found that bilateral ect left patients with more persistently impaired memory of public events as compared to right unilateral ect. effects on brain structure considerable controversy exists over the effects of ect on brain tissue, although a number of mental health associations—including the apa—have concluded that there is no evidence that ect causes structural brain damage. a 1999 report by the us surgeon general states: "the fears that ect causes gross structural brain pathology have not been supported by decades of methodologically sound research in both humans and animals." many expert proponents of ect maintain that the procedure is safe and does not cause brain damage. dr. charles kellner, a prominent ect researcher and former chief editor of the journal of ect, stated in a 2007 interview that, "there are a number of well-designed studies that show ect does not cause brain damage and numerous reports of patients who have received a large number of treatments over their lifetime and have suffered no significant problems due to ect." kellner cites a study purporting to show an absence of cognitive impairment in eight subjects after more than 100 lifetime ect treatments. kellner stated "rather than cause brain damage, there is evidence that ect may reverse some of the damaging effects of serious psychiatric illness." two meta-analyses find that ect is associated with brain matter growth. effects in pregnancy if steps are taken to decrease potential risks, ect is generally accepted to be relatively safe during all trimesters of pregnancy, particularly when compared to pharmacological treatments. suggested preparation for ect during pregnancy includes a pelvic examination, discontinuation of nonessential anticholinergic medication, uterine tocodynamometry, intravenous hydration, and administration of a nonparticulate antacid. during ect, elevation of the pregnant woman's right hip, external fetal cardiac monitoring, intubation, and avoidance of excessive hyperventilation are recommended. in many instances of active mood disorder during pregnancy, the risks of untreated symptoms may outweigh the risks of ect. potential complications of ect during pregnancy can be minimized by modifications in technique. the use of ect during pregnancy requires thorough evaluation of the patient's capacity for informed consent. effects on the heart ect can cause a lack of blood flow and oxygen to the heart, heart arrhythmia, and "persistent asystole". a 2019 systematic review and meta-analysis of 82 studies found that the rate of major adverse cardiac events with ect was 1 in 39 patients or about 1 in 200 to 500 procedures. the risk of death with ect however is low. if death does occur, cardiovascular complications are considered as causal in about 30% of individuals. procedure electroconvulsive therapy machine on display at glenside museum in bristol, england ect device produced by siemens and used for example at the asyl psychiatric hospital in kristiansand, norway from the 1960s to the 1980s the placement of electrodes, as well as the dose and duration of the stimulation is determined on a per-patient basis.: 1881 in unilateral ect, both electrodes are placed on the same side of the patient's head. unilateral ect may be used first to minimize side effects such as memory loss. in bilateral ect, the two electrodes are placed on opposite sides of the head. usually bitemporal placement is used, whereby the electrodes are placed on the temples. uncommonly bifrontal placement is used; this involves positioning the electrodes on the patient's forehead, roughly above each eye. unilateral ect is thought to cause fewer cognitive effects than bilateral treatment, but is less effective unless administered at higher doses.: 1881 most patients in the us and almost all in the uk receive bilateral ect. 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.: 1881 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. immediately prior to treatment, a patient is given a short-acting anesthetic such as methohexital, etomidate, or thiopental, a muscle relaxant such as suxamethonium (succinylcholine), and occasionally atropine to inhibit salivation.: 1882 in a minority of countries such as japan, india, and nigeria, ect may be used without anesthesia. the union health ministry of india recommended a ban on ect without anesthesia in india's mental health care bill of 2010 and the mental health care bill of 2013. the practice was abolished in turkey's largest psychiatric hospital in 2008. the patient's eeg, ecg, and blood oxygen levels are monitored during treatment.: 1882 ect is usually administered three times a week, on alternate days, over a course of two to four weeks.: 1882–1883 an illustration depicting electroconvulsive therapy neuroimaging prior to ect neuroimaging prior to ect may be useful for detecting intracranial pressure or mass given that patients respond less when one of these conditions exist. nonetheless, it is not indicated due to high cost and low prevalence of these conditions in patients needing ect. concurrent pharmacotherapy whether psychiatric medications are terminated prior to treatment or maintained, varies.: 1885 however, drugs that are known to cause toxicity in combination with ect, such as lithium, are discontinued, and benzodiazepines, which increase the seizure threshold, are either discontinued, a benzodiazepine antagonist is administered at each ect session, or the ect treatment is adjusted accordingly.: 1875, 1879 a 2009 rct provides some evidence indicating that concurrent use of some antidepressant improves ect efficacy. course ect is usually done from 6 to 12 times in 2 to 4 weeks but can sometimes exceed 12 rounds. it is also recommended to not do ect more than 3 times per week. treatment team in the us, the medical team performing the procedure typically consists of a psychiatrist, an anesthetist, an ect treatment nurse or qualified assistant, and one or more recovery nurses.: 109 medical trainees may assist, but only under the direct supervision of credentialed attending physicians and staff.: 110 devices ect machine from before 1960. most modern ect devices deliver a brief-pulse current, which is thought to cause fewer cognitive effects than the sine-wave currents which were originally used in ect. a small minority of psychiatrists in the us still use sine-wave stimuli. sine-wave is no longer used in the uk or ireland. typically, the electrical stimulus used in ect is about 800 milliamps and has up to several hundred watts, and the current flows for between one and six seconds. in the us, ect devices are manufactured by two companies, somatics, which is owned by psychiatrists richard abrams and conrad swartz, and mecta. in the uk, the market for ect devices was long monopolized by ectron ltd, which was set up by psychiatrist robert russell. mechanism of action despite decades of research, the exact mechanism of action of ect remains elusive. a review from 2022 of neuroimaging studies based on a global data collaboration resulted in a model of temporary disruption of neural circuits followed by augmented neuroplasticity and rewiring. use as of 2001, it was estimated that about one million people received ect annually. there is wide variation in ect use