For severe depression, the National Board of Health and Welfare in Sweden recommends treatment with electroconvulsive therapy (ECT). ECT was first introduced in 1938, and since then refined electrode placement and reduced current levels have led to improved treatment. Today, ECT is also administered with anesthesia and muscle relaxants. Treatments are usually administered three times a week. The patient may be admitted to a hospital for treatment or may be an outpatient who visits the clinic only for treatment sessions. As with all treatments, ECT has side-effects which include cognitive deficits such as memory loss. However, this is usually transient and resolves after treatment. Whether more long-term memory loss can occur is still debated. The mechanism of action for ECT is unclear but the effect on depression is supported by a number of clinical studies.
There are individual differences both in the response to treatment and the risk of side-effects. The reason behind this is unknown but could involve genetic or other biological variations that interact with the effect or side-effects of ECT. The PREFECT-study was launched in 2013 with the aim to identify markers that can be used to tailor treatment to individual needs.