This article originally appeared in the February 2007 Harvard Health Letter and is provided courtesy of Harvard Health Publications.

Electroconvulsive therapy
With new methods and accumulated evidence, this treatment survives its critics.

Passing an electric current through the brain to induce a seizure is not everyone’s idea of a therapeutic procedure. So it’s no surprise that electroconvulsive therapy (ECT) has been controversial ever since its invention in 1938. Fears of misuse are common, and movements to restrict or abolish the practice have had some success. It persists simply because it is sometimes a uniquely effective treatment for severe depression and other mental illnesses.

The familiar term “shock therapy” can be misleading. In the best present practice, patients feel no electric shock, because they are unconscious during the procedure. A more accurate term would be “seizure therapy.” The purpose of the electricity is to induce a generalized seizure — a rapid discharge of nerve impulses throughout the brain. Before the advent of ECT, drugs were used for the same purpose, less effectively and with more serious side effects. Even the standard word “electroconvulsive” is not strictly correct today, because a drug suppresses the convulsions (strong involuntary muscle contractions) that occur in a generalized seizure resulting from a brain malfunction (epilepsy).

Today ECT is conducted in a hospital or clinic, usually in the presence of two physicians and nursing staff. The patient is put to sleep with a short-acting barbiturate, then immobilized with the muscle relaxant succinylcholine. Two electrodes are placed on the patient’s scalp and a current is passed between them by a machine designed for the purpose. The current lasts for a second or two and the resulting seizure for 30 seconds to a minute. Heart rate, blood pressure, and breathing are monitored throughout to be sure no vital functions are interrupted.

Patients may have a mild headache or suffer some confusion and disorientation for a few minutes after each session. The treatment is repeated two to three times a week, a total of about a dozen times or until recovery — whichever comes first. Sometimes patients are hospitalized throughout, sometimes not.

Does it work?
In controlled studies, ECT is consistently found to be as effective as drugs or more so. The rate of response to antidepressant drugs runs from 40% to 70%. ECT has a response rate of 70% to 90%, even though it usually isn’t attempted until other treatments fail. Patients who are not helped by drugs often respond to ECT, and it works faster than drugs — requiring, on average, two to three weeks instead of six to eight weeks for significant improvement. So it is often the first choice in an emergency, especially when the patient is psychotic, suicidal, not eating, or unable to get out of bed.

Some think that formal clinical trials paint too hopeful a picture. One study of real-life ECT found that the rate of remission (recovery from an episode of depression) was only 30% to 45%. The survey authors think that in practice, as opposed to clinical trials, the treatment is often stopped too soon, when patients have remaining symptoms that make them more prone to relapse.

ECT has fewer side effects than drugs and is less risky for people with cardiovascular disease, so it may be preferred for pregnant women, older people, and the physically ill. The American Academy of Child and Adolescent Psychiatry says that ECT should be considered for an adolescent when the symptoms are severe or the patient has not responded to two antidepressant drugs. Both the patient and his or her legal guardian must give consent.

ECT can also be used to treat mania, the uncontrollable elation that alternates with depression in bipolar disorder. It is recommended mainly when lithium, anticonvulsants, and antipsychotics, the standard drug treatments, are ineffective or have serious side effects. A practical hurdle is that manic patients may be more reluctant to consent to ECT.

In the treatment of psychosis, ECT is helpful mainly when severe symptoms develop suddenly in a patient who has been in good mental health. It may also be recommended when delusions, hallucinations, or agitation must be suppressed quickly. For more lasting effects in the treatment of schizophrenia, it usually compares unfavorably with antipsychotic drugs.

How can relapse be prevented?
Like other treatments for depression, ECT is no cure. About a third of the most severely depressed patients relapse within four months, and half within a year. The high relapse rates are not surprising, given that most people who undergo ECT have particularly severe symptoms that were unaffected by medications and psychotherapy.

To prevent relapse after successful ECT, patients may be given antidepressants — sometimes the same drugs that originally failed. Another solution is maintenance or continuation ECT — further seizure treatments once a week, once a month, every few months, or whenever symptoms reappear. Tests of its effectiveness are rare. One study compared drugs alone to maintenance ECT plus drugs for patients who recovered with ECT. After five years, relapse rates were 27% for maintenance ECT, 82% without it. But patients were not assigned to the two groups at random, so the high success rate might have been due to extra attention and closer monitoring. Other studies have found no difference between continuing drug treatment and continuing ECT for patients in general, but different patients may require different approaches.

How does it work?
ECT has been compared to kicking a machine to start it up. The image may not be flattering or reassuring, but it does reflect the fact that the treatment affects many brain pathways, nerve receptors, neurotransmitters, and endocrine systems. It’s not known which of these effects are therapeutic. There is some evidence that patients are more likely to recover if their electroencephalograms (EEGs) increasingly show a pattern known as slow wave activity during the treatment. Brain waves return to their original state two months after the treatment ends. Other speculations are that ECT changes the output of certain neurotransmitters or redresses an imbalance of stress hormones.

Some think the brain draws on its powers to combat the seizures and in the process conquers depressive and psychotic symptoms as well. That model suggests how it is possible to treat depression and mania either with ECT or with anticonvulsant drugs, which seemingly have opposite effects. In fact, the danger of spontaneous seizures falls during ECT. But antidepressant drugs do not lower the risk of seizures, and benzodiazepines, which do suppress seizures, are not a treatment for depression. Most likely there is no single explanation for the therapeutic effects of ECT that applies to all patients.

What are the dangers?
Despite understandable fears, ECT does not cause any damage visible on brain scans, either in human beings or in animals subjected to much more prolonged electrical seizures. The most common complaint and main concern of patients is memory loss. Tests show that memory, both retrograde (recall of events that occurred before the treatment) and anterograde (ability to absorb new knowledge afterward) declines as the treatment proceeds. It usually returns to normal within a few weeks — but not necessarily for all patients and in all respects.

Everyone agrees that most patients suffer some permanent loss of memory for events during the treatment and a few days to weeks before. After that experience, some may become more concerned about everyday forgetfulness and the normal decline of memory with age.

The risk of more serious and lasting memory loss is disputed, but most studies find that it is not common. In one study, for example, 20 patients receiving maintenance ECT for a year had the same cognitive test scores as 10 patients who were never given ECT. Adolescents treated with ECT for depression or bipolar disorder were found to have normal memories three years later.

Researchers at the New York State Psychiatric Institute conducted a careful long-term study of ECT’s effects on memory and intellectual functioning. Before and after treatment and again six months later, several hundred patients were given tests of retrograde and anterograde memory, reaction time, attention, and overall cognitive functioning. They also answered a questionnaire on autobiographical memory.

Most test scores declined by the end of treatment, then recovered. Six months later, patients were scoring better than before treatment — a reflection of severe depression’s damaging effects on the mind. But many still scored poorly on the test of autobiographical memory, and a little more than 10% showed severe deficits on this test. Women and older people were most susceptible.

The placement of electrodes and the type of electric current made a big difference. Originally, electrodes were placed at the temples on opposite sides of the head (bilateral placement). An increasingly popular alternative is to place them both on the same side (unilateral placement), usually the right. Another innovation is a machine that produces brief intermittent pulses instead of continuous electrical stimulation. And the dose of electricity can now be adjusted individually so that it is just strong enough to cause a seizure.

The New York researchers found that following these newer procedures greatly reduced the risk of memory loss and slow reaction times. Some practitioners think unilateral ECT and brief pulses are less effective than bilateral placement and continuous stimulation, but others are now convinced that if the dose of electricity is adequate, these methods can work as well as the older ones with far fewer side effects.

If physicians choose patients carefully and do the procedure correctly, the risk of serious and lasting memory loss is probably low. But averages do not account for individual variation and they may not be reassuring to people who have a subjective sense that their memory is less sharp. Patients and physicians must decide when the potential benefits outweigh the risks.

What is the standing of ECT today?
Despite its effectiveness, electroconvulsive therapy is not widely practiced. In the United States, about 100,000 patients receive the treatment each year. Restrictive consent procedures limit its use, especially for patients who are psychotic or otherwise incompetent. Lack of facilities and lack of experience also create obstacles. In 1993, a law was passed in the state of Texas requiring detailed reports on each use of ECT. In a review of records for 1993–1995, researchers found that the treatment was available in only one of 13 state mental hospitals, and only 6% of psychiatrists had authorized it. Ninety-percent of these cases involved severe mood disorders, and about half of the patients were over 65. Another study found that fewer than 2% of patients in New York state psychiatric hospitals received ECT. The treatment is prescribed more often in private institutions and for white and middle-class patients. Whether it is used too much or too little is disputed. Some say blacks, Hispanics, and the poor are being deprived; others say they are being spared.

The search is on for electromagnetic devices that have the virtues of ECT but inspire fewer unreasonable fears or create fewer genuine risks. In early 2007, the FDA will be deciding whether or not to approve repetitive transcranial magnetic stimulation (rTMS) as a treatment for depression. This technique takes advantage of the ability of strong magnetic fields to create electrical currents. A coil is held near the scalp. When it is electrified, the resulting magnetic field is strong enough to activate nerve cells in the brain. Since it affects a very small area, rTMS has much milder and more localized effects than ECT. It does not require anesthesia, but there is limited information about its effectiveness.

Magnetic seizure therapy uses the same apparatus as rTMS — a magnetic coil held near the scalp — but the generator is powerful enough to cause a seizure. Like ECT, magnetic seizure therapy requires anesthesia, but in theory it might have more selective effects. Unlike electrical energy, magnetic energy is not scattered by the skull, so the current might be directed more precisely to avoid brain regions that are critical for memory. At present this treatment is experimental.

Meanwhile, ECT continues to restore the health and sometimes save the lives of people with the potentially lethal disorders of severe depression, mania, and acute psychosis. It has been compared to cardioversion, the procedure in which an electric current reinstates normal rhythms in a faltering heart. For the patients who suffer most with mood symptoms, nothing better than ECT has been devised. That is the most important reason for its survival through nearly 70 years of doubts, fears, and political controversy.