Benefits & Limitations of ECT for Depression

Ph.D., CPsychol., AFBPsS, Health Professional

Electroconvulsive therapy (ECT), sometimes called shock treatment, is a form of therapy for depression. ECT remains a controversial form of therapy because so little is actually known about how it works. One of the reasons it continues to be used is because it achieves a rapid therapeutic effect where no existing medication or other form of therapy is able.

In order for ECT to be prescribed the patient must be severely depressed, or suicidal, be unresponsive to drug therapies, or suffer such severe side-effects from medication normally prescribed for depression that drugs are ruled out. As antidepressant medication can take several weeks before a therapeutic effect is seen, if at all, it is less practical in cases where people express suicidal thoughts or who may have attempted suicide. Furthermore, very severe cases of depression can lead to extreme levels of apathy where the person stops eating and drinking. In both of these examples the critical factor is time. ECT may also be used in less critical circumstances, particularly if the patient has a history of responding positively.

The treatment is administered under controlled medical conditions, either in a dedicated ECT suite or theatre. The patient is fully sedated then given a muscle relaxant. The shock is delivered via electrode pads placed either to one or both sides of the head. If placed on either side of the head the shock will produce a seizure affecting the whole brain. If placed to one side of the head a seizure a seizure will occur in that hemisphere. Sufficient electrical current must be sent into the brain to cause a seizure (a fit), which usually lasts a few seconds. The whole procedure, including preparations, anesthesia and recovery takes maybe 30 minutes or less. Electrical stimulation to the whole brain seems to have a more rapid effect but produces a greater likelihood of side effects.

On average, a course of ECT is around 6-9 treatments over two or three times a week. Dosages and timing do sometimes vary according to therapeutic effect and/or the need to reduce side effects. Although a consent-based treatment there are exceptional circumstances where treatment may be enforced. Regulations as to enforced treatment protocols may vary between States and countries.

Although ECT can have a rapid and dramatic positive effect these tend to be short term. The relapse rate is quite high and one study (Sackeim et al., 2001) found nearly all remitted patients relapsed within a six month period if they did not continue with antidepressant medication.

The side effects, both short and long-term, represent a continuing concern. Immediately after ECT treatment many patients complain of headaches, nausea, confusion, muscle aches and fatigue. These symptoms tend to pass fairly quickly. The most commonly reported long-term side effect is retrograde amnesia, that is, loss of memory for events going back months or sometimes years. Amnesia usually improves in the months following treatment except for events immediately preceding ECT where it often remains. There is no evidence that ECT causes structural damage to the brain.


Sackeim, H.A., Haskett, R.F., Mulsant, B.H., et al (2001) Continuation pharmacotherapy in the prevention of relapse following electroconvulsive therapy: a randomized controlled trial. Journal of the American Medical Association, 258, 1299-1307.