How Effective and Safe is Electroconvulsive Therapy for Treating Depression?

What you need to know

• Electroconvulsive therapy (ECT) is the most effective treatment for severe, psychotic, or treatment-resistant depression, with remission rates of 52-75%.
• ECT is very safe when performed properly, with extremely low mortality rates. It does not cause brain damage or increase risk of dementia.
• Short-term memory and cognitive effects are common but typically resolve within weeks. Effects on autobiographical memory are less clear.
• ECT techniques have been refined over time to maximize effectiveness while minimizing side effects.
• Continued treatment after ECT, either with medications or maintenance ECT, is important to prevent relapse.

What is electroconvulsive therapy?

Electroconvulsive therapy (ECT) is a medical procedure used to treat severe mental illnesses, particularly depression. During ECT, a brief electrical current is applied to the brain to trigger a short seizure, typically lasting about 30 seconds. The patient is under general anesthesia and given muscle relaxants, so they do not feel anything or have visible convulsions.

A typical course of ECT involves 8-12 treatments given two or three times per week. ECT is most commonly used for severe depression that has not responded to other treatments. It can also be used for bipolar disorder, schizophrenia, and catatonia.

How effective is ECT for depression?

Multiple studies have found ECT to be highly effective for treating depression, especially severe or treatment-resistant cases. Some key findings on ECT’s efficacy include:

• Remission rates (full recovery from depression) of 52% in clinical trials and up to 75% in large real-world studies. This is remarkable considering most patients receiving ECT have already failed to improve with multiple medications and therapies.

• In a meta-analysis comparing ECT to other treatments, ECT had the highest probability (65%) of being the most effective therapy for depression.

• ECT works more rapidly than medications, often providing significant relief within 2-4 weeks.

• ECT is particularly effective for depression with psychotic features, with remission rates around 80-90%.

The high efficacy of ECT is why many experts argue it should be considered earlier in treatment for severe depression, rather than as a last resort. A recent economic analysis found ECT to be cost-effective if used after just two failed medication trials.

Is ECT safe?

Despite its somewhat intimidating nature, ECT is actually very safe when performed properly by trained medical professionals. Some key points about ECT safety:

• Mortality rates are extremely low - about 2.1 deaths per 100,000 treatments. This is comparable to minor surgical procedures.

• There is no evidence that ECT causes brain damage. In fact, studies have shown ECT does not increase risk of dementia or stroke.

• Common side effects like headache, muscle pain, and nausea are usually mild and can be managed with simple medications.

• Serious medical complications are rare due to pre-screening of patients and close monitoring during the procedure.

• ECT may actually reduce overall mortality in patients with depression, likely due to treating the underlying illness.

The main safety concern with ECT relates to its effects on memory and cognition. However, these effects are typically short-term:

• Most cognitive effects resolve within a few weeks after completing ECT.

• By several months after ECT, cognitive performance on tests is often better than before treatment, likely due to improvement in depression.

• Effects on autobiographical memory (recall of personal life events) are more variable between individuals and harder to measure objectively. Some patients do report persistent gaps in memory of events around the time of ECT.

How has ECT technique evolved?

Since its development in the 1930s, ECT technique has been refined to maximize efficacy while minimizing side effects:

• Early ECT used sine wave electrical stimulation, which caused more cognitive side effects. Modern ECT uses brief pulse or ultra-brief pulse waveforms that are more efficient.

• Electrode placement options now include unilateral treatment (on one side of the head) which can reduce cognitive effects compared to bilateral placement.

• Electrical dosage is now carefully calibrated for each patient to use the minimum necessary to produce a seizure.

• Anesthesia and muscle relaxants are used to prevent injury and discomfort.

• Close monitoring of seizure quality allows clinicians to adjust treatment parameters.

Ongoing research is exploring further refinements like focal electrically administered seizure therapy (FEAST) that may offer additional cognitive benefits.

What factors predict response to ECT?

While ECT is highly effective overall, certain clinical factors are associated with better outcomes:

• Presence of psychotic features is the strongest predictor of remission with ECT.

• Older age is modestly associated with better response, though the effect is small.

• Greater overall depression severity predicts higher response rates but not necessarily full remission.

• Longer duration of the current depressive episode and treatment-resistance are associated with somewhat lower remission rates, though ECT is still more effective than medications in these cases.

Importantly, melancholic features and bipolar vs. unipolar depression do not seem to significantly impact ECT outcomes.

What happens after ECT?

While ECT can produce rapid improvement in depression, relapse is common without ongoing treatment. Key points about post-ECT care:

• Relapse rates after ECT are similar to those seen after medication treatment of resistant depression - about 37% at 6 months and 51% at 12 months.

• Continuing antidepressant medication after ECT is crucial. Patients who stop all treatment have double the relapse rate at 6 months.

• Some patients benefit from a gradual taper of ECT sessions rather than abrupt discontinuation.

• Maintenance ECT (periodic treatments to prevent relapse) is an option for patients who respond well to ECT but relapse on medications alone.

• A flexible, individualized approach considering both medications and potential maintenance ECT offers the best chance of sustaining improvement.

Conclusions

• ECT remains the most effective treatment available for severe, psychotic, or treatment-resistant depression.
• Modern ECT is safe and well-tolerated, with refinements in technique minimizing cognitive side effects.
• ECT should be considered earlier in treatment algorithms for severe depression rather than as a last resort.
• Ongoing research into ECT mechanisms may lead to new depression treatments and insights into the biology of mood disorders.
• Overcoming stigma and misinformation about ECT is crucial to ensure patients have access to this highly effective treatment when needed.