Depression is the most common mood disorder worldwide. The World Health Organization estimates that 3.8% of the world's population is affected by depression, leading to significant morbidity and mortality.

Depression. World Health Organization. September 13, 2021.

 

Antidepressants and psychotherapy are the two main approaches used to treat depression.

Li M, Yao X, Sun L, et al. Effects of electroconvulsive therapy on depression and its potential mechanism. Front Psychol. 2020;11:80.

Electroconvulsive therapy (ECT) is an additional treatment modality utilized as a second- or third-line therapy in patients who are resistant to medication and psychotherapy.

 

What does the latest research say about the efficacy of ECT and why is it controversial? Let’s take a closer look.

 

More about ECT

ECT was first introduced more than half a century ago and is currently utilized as a last resort to treat patients with severe mental disorders, such as depression or bipolar disorder. The procedure involves applying an electrical stimulus to produce a generalized seizure.

Since its first recorded use in 1938, significant improvements have been made to ECT, whereby the US Food and Drug Administration (FDA) and the National Institute for Health and Care Excellence (NICE) have evaluated the treatment and approved its use.

 

ECT efficacy and safety

ECT has been shown to be a fairly safe and effective method for the treatment of depression. Studies have shown that ECT alone, particularly bilateral ECT, leads to a fast therapeutic response and a high likelihood of remission in patients with severe unipolar major depressive disorder.

For patients with treatment-resistant bipolar depression, the results of ECT were superior to those of medication.

In addition to its effect on depression, continuation ECT showed benefit in patients with schizophrenia and schizoaffective disorder.

Although ECT is generally considered safe, there are potential risks and side effects.

Mayo Clinic Staff. Electroconvulsive therapy (ECT). Mayo Clinic. October 12, 2018.

These include:

 

• Confusion: Patients who receive ECT may experience confusion, lasting anywhere from minutes to hours. In rare situations, confusion could persist over multiple days or longer.

• Memory loss: Patients may suffer from retrograde amnesia. However, for most individuals, memory loss improves within a few months after the end of treatment.

• Medical complications: During ECT, heart rate and blood pressure are elevated which may lead to serious cardiac problems.

• Physical side effects: After an ECT treatment, some patients experience headache, nausea, muscle aches or jaw pain.

 

Mechanism of ECT

While inducing seizures in the human brain has been shown to be effective in treating psychiatric disorders, how seizure activity improves neuropsychiatric symptoms is still not completely understood.

Singh A, Kar SK. How electroconvulsive therapy works? : understanding the neurobiological mechanisms. Clin Psychopharmacol Neurosci. 2017;15(3):210–221.

 

The underlying mechanism governing ECT's effectiveness can be explained by neurophysiological, neurobiohemical, and neuroplasticity hypotheses.

Neurophysiological

The electrical impulse arising from ECT electrodes stimulates neurons in the brain by altering ion concentrations, as well as the internal electrical environment. It is thought that the therapeutic effect of ECT results when a group of depolarized neurons fire at the same time to produce a convulsion.

ECT has also been shown to alter cerebral blood flow as well as glucose metabolism. Studies have shown an increase in cerebral blood flow in the area with seizure activity. ECT may also induce changes in the blood brain barrier, along with alterations to the functional integrity of the cerebral cortex.

Neurobiochemical

ECT can influence the expression and release of neurochemicals in the brain including neurotransmitters, neurotrophic factors, transcription factors, and hormones.

It affects the transmission of neurotransmitters such as serotonin, dopamine, epinephrine, norepinephrine, acetylcholine, and endogenous opioids, and acts at the level of neurotransmitter synthesis, release, receptor binding, and reuptake.

Neuroplastic

Changes to the volume of brain structures have been reported in psychiatric disorders. Studies have shown that ECT can trigger changes in the volume of the whole brain as well as in the white matter and gray matter, as well as other structures within the brain.

ECT can also induce changes at the level of neurons, dendrites, synapse, and vasculature, along with alterations to glial cells and their processes.

 

Controversy surrounding ECT

These in part originated from negative media portrayals of ECT. However, even scientists and clinicians have not been in agreement over its use.

A 2022 article published in Epidemiology and Psychiatric Sciences examined the evidence cited by ECT opponents to call for a ban of this treatment modality in the UK.

Meechan CF, Laws KR, Young AH, et al. A critique of narrative reviews of the evidence-base for ECT in depression. Epidemiol Psychiatr Sci. 2022;31:e10

 

Advocates of banning ECT noted it should be suspended due to permanent memory loss being of significant risk, as well as the possible risk of death. In addition, there were concerns that well-designed, randomized, placebo-controlled studies were needed to investigate ECT’s effectiveness.

However, investigators showed that such arguments were based on selective, poor-quality assessments of existing literature. The authors concluded that upon a closer look at the research, ECT was found to be effective for severe depression.

 

Comparison to psychopharmacology

Currently, only a small percentage of patients who are candidates for ECT receive it in the US.

Sackeim HA. Modern electroconvulsive therapy: vastly improved yet greatly underused. JAMA Psychiatry. 2017;74(8):779–780.

 

For example, it was found throughout nine states that only a mere 1.5% of patients hospitalized with severe mood disorders had been provided with ECT as a treatment option.

The two primary factors of limitation included a likelihood for relapse alongside adverse cognitive effects. However, in recent years, there have been significant improvements to ECT that have substantially improved these limitations.

An article published in the American Journal of Psychiatry compared ECT’s efficacy to that of pharmacological treatment in patients with treatment-resistant bipolar depression.

Schoeyen HK, Kessler U, Andreassen OA, et al. Treatment-resistant bipolar depression: a randomized controlled trial of electroconvulsive therapy versus algorithm-based pharmacological treatment. AJP. 2015;172(1):41–51.

Investigators concluded ECT was significantly more effective than pharmacological intervention.

 

At the end of a 6-week treatment period, the ECT group had lower average scores on the Montgomery-Åsberg Depression Rating Scale, the 30-item version of the Inventory of Depressive Symptomatology-Clinician-Rated, and the Clinical Global Impression for Bipolar Disorder.

While the response rate was vastly higher when comparing the ECT group to that of the pharmacological treatment group, the remission rate was not different between the groups.