Electroconvulsive therapy (ECT)

Electroconvulsive therapy (ECT) is a treatment that has been used in psychiatry since the 1930s. The procedure involves passing an electric current between two electrodes placed on the scalp of the patient to induce a generalised seizure. This article outlines the history, indications, procedure, and side effects of this therapy.

History of Electroconvulsive Therapy 

Do you know the origins of ECT?

Chemical agents to initiate seizure activity have been used for the treatment of psychiatric disorders since the sixteenth century. These treatments were used for a variety of disorders and often lead to mixed results owing to their complex side effect profiles; it was in the twentieth century that scientific reasoning and the beginnings of trial design enabled the therapeutic effect of this therapy to be properly assessed.

This therapy was hypothesised and developed by Dr Laszló Meduna, a neuropathologist and neuropsychiatrist from Hungary. His original hypothesis revolved around the observed glial numbers in brain samples taken from patients with epilepsy being higher than those with schizophrenia. He tested whether inducing seizure activity would increase glial cell numbers in those with catatonic schizophrenia. This theory has subsequently been proven incorrect, yet the outcome of the therapy in certain patients remained positive.

Dr Meduna originally used chemical agents (Camphor and Metrazol) before a switch to an electrical-based therapy in 1938 by Dr Lucio Bini and Dr Ugo Cerletti. An electrical-based therapy had far lower rates of status epilepticus than these chemical-based agents. 

Proposed mechanisms of action

There is no consensus regarding how ECT produces its clinical effect. Numerous experiments in tissue and animal models have shown alterations to neurotransmitter activity, hormonal activity in the HPA axis, brain structure volume changes, and epigenetic and cerebral blood flow alterations to name but a few. However, it is noted that the therapeutic effect of ECT for major depression and mania is faster and more effective than pharmacological agents in the acute setting, but the side effect profile of these pharmacological agents is more acceptable. 

Treatment process

The patient has firstly consented and if this is not possible, then a best-interest decision is made by the clinical team with the patient advocate or next of kin involved.

The patient is lying supine for the procedure, with the side rails up and cushions to protect them from injury. A cannula is inserted to administer the general anaesthetic and muscle relaxant. The muscle relaxant reduces muscle contractability, reducing the injury risk. The electroencephalogram (EEG) leads are placed on the scalp to monitor seizure activity during the procedure. The two electrodes are then placed on the scalp, either across both hemispheres (bilaterally) with placement on both temples or across one hemisphere (unilaterally). A bilateral approach has better clinical efficacy, but side effects are more common than unilateral placement. The current passes through the electrodes and this initiates a generalised tonic-clonic seizure. The aim is for this to last for approximately 30 seconds with spontaneous self-termination.

Following the treatment, the patient is observed for a short period before discharge from the ECT clinic the same day. Discharge can be into the community or the ward depending on patient circumstances.

NICE Guidelines for ECT

 NICE have a dosing protocol for ECT. The dose administered typically starts off low and increases until an adequate seizure length is reached (around 30 seconds). The length of the seizure is measured using EEG tracing throughout the procedure. 

The typical cycle of sessions is biweekly for up to twelve weeks, meaning 6-12 sessions in total. Some patients can go on to have maintenance monthly sessions afterwards to prevent clinical relapse. A future relapse would usually only be treated with ECT if the previous cycle was shown to be clinically beneficial. 

NICE Indications

NICE Indications:
-Severe depressive illness
-Prolonged or severe manic episode

NICE also state that ‘ECT is used only to achieve rapid and short-term improvement of an individual’s severe symptoms after an adequate trial of other treatment options has proven ineffective and/or when the condition is considered to be potentially life-threatening.’ 

A Common Scenario

A Common Scenario:
An example that you may come across is an individual with a severe depressive illness who has stopped eating and drinking (life-threatening), whereby pharmacological therapy would take up to six weeks to work, making ECT indicated given the risk of morbidity and mortality. 


 Side effects and risks of treatment

 The side effects can be split into acute and chronic, which are listed in the table below.

 The main potentially distressing side effect is retrograde or anterograde amnesia. This is increased when the current is passed through both hemispheres, or the dominant hemisphere when unilateral electrode placement is used. Serial cognitive assessments are conducted to monitor for these side effects, the assessments of choice are typically an Addenbrooke’s Cognitive Examination III (ACEIII) or a Montreal Cognitive Assessment (MoCA). 

Acute side effectsChronic side effectsContraindications
General anaesthetic associatedAnterograde/ retrograde amnesiaAbsolute- phaeochromocytoma
Anterograde/ retrograde amnesiaCognitive impairment (elderly most at risk), causation unclearRelative- recent MI/ Stroke, COPD/asthma, COPD/ Asthma,
INR >3.5
Status epilepticus (low frequency)

Take-home messages

-NICE has strict criteria for the indications for ECT and this decision will be senior-led with the involvement of the MDT

 -The procedure itself still attracts a lot of public and media attention and this should be taken into consideration when discussing and consenting the patient and their next of kin.  

 -A baseline formal cognitive assessment (ACEiii or MoCA) will be required when referring for ECT, this is the most likely input of the junior doctor for these cases.


NICE Guidelines for ECT

Gazdag G, Ungvari GS. Electroconvulsive therapy: 80 years old and still going strong, G Gazdag and GS Ungvari. World J Psychiatry 2019.

How Electroconvulsive Therapy Works?: Understanding the Neurobiological Mechanisms, Amit Singh and Sujita Kumar Kar, Clinical Psychopharmacology and Neuroscience 2017.

Written by Dr Isobel Platt, FY1
Edited by Dr Gareth Smith, Consultant Psychiatrist

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