Memory Loss And Cognitive Effects Of ECT

  • Morgan Keogh MBBS, Medicine, King's College London, UK/li>
  • Tanvi Shukla Master of Pharmacy - MPHARM, Nirma University


Electroconvulsive Therapy (ECT) is a process whereby pulses of electricity are applied to a patient’s head, safely inducing controlled epileptic seizures.1 Patients will be typically anaesthetized and under-induced muscle paralysis to prevent injury to themselves or to those performing the procedure. ECT stems from the concept of using one disease as a curative option for another, whereby induced epilepsy was postulated to be curative in those with severe mental illness.2 Early interventions utilizing ECT were found to be extremely effective, restoring large degrees of psychological functionality in those treated.2 Since those early trials, the techniques underpinning ECT have been refined and perfected, ensuring it remains a robust and effective treatment for patients with debilitating mental illness. Often reserved for those patients in whom psychological therapies have failed, ECT remains one of the most potent treatments for those affected by resistant and severe disease.1 Within this article, we will explore the mechanisms underpinning ECT and its associated side effects, hoping to provide a comprehensive and thorough overview of the intervention. 

Understanding ECT

ECT is given in hospitals, with some patients receiving the treatment as in-patients or as out-patients.3 Typically, a waiting room, the procedure room, and a recovery room will be present, with medical staff at hand to ensure your safety and welfare throughout the process. In the days preceding the procedure, your healthcare provider will likely perform some tests to ensure it is safe for you to receive anaesthesia.3 These will likely include an ECG and some routine blood tests. It is important that you do not eat or drink anything for at least 6 hours before the procedure, although sips of water may be permitted up to 2 hours before.3 If you are taking any medication prior to the procedure, you must ask the ECT as to what they advise regarding their use. 

During the procedure 

Prior to the procedure, a member of the ECT team will come to ensure they have your consent before commencing with the therapy. They may also perform some physical checks if these have not been performed by this point. When ready, the ECT staff will take you into the ECT suite, attaching numerous monitoring devices to ensure sufficient measurements of your heart rate, blood pressure, oxygen levels and brain waves.3 You will be given oxygen to breathe through a mask, and the anaesthetic will be injected through the back of your hand. 

Whilst asleep, the anaesthetist will administer a muscle relaxant and insert a mouth guard to protect your teeth.3 Two metal discs will then be placed on your head. In bilateral ECT, these discs will be placed on either side of your head, whilst in unilateral ECT, these will be placed on the same side of the head.3 The ECT machine will then release a series of brief electrical pulses lasting 3-8 seconds.3 These pulses will induce a controlled seizure, which will last 40-120 seconds.3 During this seizure, your body will stiffen, with twitching commonly seen in the hands, feet and face. The muscle relaxants will reduce the amount your body moves, however, reducing the possibility of any harm. 

After the procedure 

After the procedure, you will be moved to the recovery room. The muscle relaxants used will wear off within a few minutes, although you may feel drowsy as you wake. An experienced nurse will then measure your blood pressure whilst asking a series of simple questions to assess how much you have awoken.3 A monitor known as a pulse oximeter will be placed on your finger to ensure your oxygen levels are satisfactory. When you first wake, you may find you are disorientated and thus may not be aware of where you are. After half an hour or more, these effects should disappear, with the nurse asking further questions to assess this. You will then leave the site when you feel physically well. In total, this whole process should last an hour or less.3 It is important that for 24 hours after, you do not sign any legal documents or consume alcohol.3 You should also have a responsible adult with you for at least 24 hours.

How does ECT work and who is selected for it? 

ECT remains a very effective treatment for severe mental illness, with 68% of patients between 2018 and 2019 reporting to be ‘much-improved’ or ‘very much improved’ following the treatment.3 Despite this, a full understanding of the mechanisms underpinning its success remains to be fully elucidated. It is thought that, primarily, ECT works on neurotransmitter systems, chemical systems within the brain that are responsible for the conduction of signals.1 Dysfunction or dysregulation of these symptoms are thought to be causative of depression, therefore indicating one mechanism by which ECT can be useful. ECT is also thought to act on three important glands: the pituitary, hypothalamus, and adrenal glands.1 Through acting on these glands, ECT is thought to reduce levels of cortisol (the stress hormone), a hormone which is found to be abnormally high in those with severe depression.1 Both of these systems are among the many that are thought to be affected by ECT, although a definitive understanding of these remains to be sought. 

As discussed throughout, ECT is typically reserved for those with severe mental illness. Whilst focus appears to be on those with severe depression, ECT has also been shown to be effective in those with illnesses such as schizophrenia and OCD.1 ECT is considered ‘first-line’ (i.e., considered before any other treatment) in patients with the following illnesses: 

  • Depression that is either melancholic, catatonic, or psychotic.1
    • Melancholic depression: depression where a patient's thoughts, speech and movements are slowed. These patients typically tend to have accompanying weight loss and disruptions to their sleep.4
    • Catatonic depression: patients typically tend to present with immobility, staring, and rigidity.5 
    • Psychotic depression: these patients tend to display symptoms of psychosis, with hallucinations and delusional thought patterns common. 
  • Schizophrenia (which cannot be handled in psychiatric wards)1
  • Severe psychosis or psychotic symptoms. 
  • Neuroleptic malignant syndrome.1

ECT is then typically used as a ‘second line’ (i.e., where other treatments have failed) in conditions such as:1 

Rarely, ECT has been documented to be used as a ‘last-resort’ option for the following conditions:1

Memory loss in ECT 

Memory loss is a common side effect in those who have received ECT, although its severity and nature can vary. For example, up to 40% of patients can experience memory loss whilst receiving ECT.3 Patients will typically describe being unable to recall specific conversations they had during the procedure or may forget at what time they arrived, etc.3 Approximately a fifth of patients (17%) will go on to develop more severe memory issues however.3 Whilst these tend to clear in most people after 2 months, in some, they persist, with issues such as anterograde amnesia and retrograde amnesia developing. 

  1. Anterograde Amnesia
    1. Anterograde amnesia refers to an inability to learn/memorize new things following ECT.6 Despite this, the ability to learn new materials recovers quicker than the ability to retain those materials.6
    2. Retrograde amnesia refers to the inability to recall existing memories.6 This is arguably the most debated issue surrounding ECT use, with many patients wishing not to risk sacrificing existing memories. Inextricably linked with a sense of personal identity, this fear can sometimes be a significant contributor to patients’ inertia regarding participation. ‘Autobiographical’ memory loss appears to be the most common feature of retrograde amnesia, with some patients forgetting details of their school, college, or family life.6

Sometimes, these memories can partially or fully recover, although the gaps can be permanent in some instances.3 Recent research has suggested that 7% of people receiving unilateral ECT report some degree of persistent memory loss 12 months after receiving treatment.3 Importantly, ECT has been shown to not be associated with an increased risk of brain damage, epilepsy, or stroke.3 

Managing ECT-associated memory loss 

Many trials have investigated potential pharmacological therapies for ECT-induced memory loss. Some trials using drugs such as thyroid hormones and donepezil have shown promising results in both animal and human studies.6 Despite this, none have shown persistent results with regard to improvements in memory loss.6 Medications have, therefore, not been licensed for the management of ECT-induced memory loss. 

Beyond memory: cognitive effects of ECT 

As discussed, all patients receiving ECT will wake feeling disoriented and confused. However, the severity and duration of this confusion/disorientation may vary with the age of the patient, dosage and type of the anaesthetic, and the medications patients may be taking to manage their mental illness.1 In particular, sedatives, antipsychotics, and lithium are known to augment this period of confusion.1

Cognitive side-effects are established to be more common in those receiving unilateral and higher-dose ECT.1 Notably; patients may notice differences in their attention spans and abilities to concentrate, with these tending to decrease.1 These cognitive effects can be difficult to discern from the cognitive effects of underlying illness, and in cases where disease persists, this differentiation can become even more complex.1 Despite these side effects, cognitive impairments can rapidly improve within 1 to 4 weeks, with follow-up studies frequently showing complete resolution of these symptoms. 


ECT remains an effective and powerful treatment of severe mental illness. Using metallic discs placed on either side of the head, patients receiving ECT will be anaesthetised and provided with muscle relaxants. Using short, frequent electrical pulses, controlled seizures are induced. These pulses are thought to act on neurotransmitter systems and the pituitary, hypothalamus, and adrenal glands. Through these proposed mechanisms, ECT is thought to be effective in treating severe depression, mania, psychosis, schizophrenia and OCD. Used first-line in some patients, ECT may be considered an option in those with disease where treatment has failed. The most notable of the potential side effects induced by ECT are those relating to memory loss. Causing significant retrograde and anterograde amnesia in some patients, many find the prospect of forgetting details of their lives a driving factor behind their decision to not undergo the procedure. Whilst memory issues can be resolved, small numbers of patients do report persistent and permanent gaps in their memory. Currently, there are no licensed treatments to address these deficiencies. ECT can also cause degrees of cognitive impairment, with patients noticing their ability to focus and concentrate declining. Certain drugs, such as antipsychotics, can also augment the disorientation and confusion experienced by patients following ECT. 


  1. Baghai TC, Möller H-J. Electroconvulsive therapy and its different indications. Dialogues Clin Neurosci [Internet]. 2008 [cited 2024 Jan 19]; 10(1):105–17. Available from:
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  3. Electroconvulsive therapy (ECT) | Royal College of Psychiatrists. [Internet]. [cited 2024 Jan 19]. Available from:
  4. PARKER G, FINK M, SHORTER E, TAYLOR MA, AKISKAL H, BERRIOS G, et al. Issues for DSM-5: Whither Melancholia? The Case for Its Classification as a Distinct Mood Disorder. Am J Psychiatry [Internet]. 2010 [cited 2024 Jan 19]; 167(7):745–7. Available from:
  5. Rasmussen SA, Mazurek MF, Rosebush PI. Catatonia: Our current understanding of its diagnosis, treatment and pathophysiology. World J Psychiatry [Internet]. 2016 [cited 2024 Jan 19]; 6(4):391–8. Available from:
  6. Andrade C, Arumugham SS, Thirthalli J. Adverse Effects of Electroconvulsive Therapy. Psychiatric Clinics of North America [Internet]. 2016 [cited 2024 Jan 19]; 39(3):513–30. Available from:
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Morgan Keogh

MBBS, Medicine, King's College London, UK

I am a fourth year Medical Student at Kings College London, currently intercalating in a BSc in Cardiovascular Medicine. I have a strong interest in Cardiology, Acute Internal Medicine and Critical Care. I have also undertaken a research project within the field of Cardiology whereby I explored the efficacy of a novel therapeutic test at detecting correlations between established clinical characteristics and salt-sensitive hypertension. I have broad experience with both the clinical and theoretical aspects of medicine, having engaged with a wide array of medical specialities throughout my training. I am currently acting as a radiology representative within the Breast Medicine Society and have experience with tutoring at both GCSE and A-level. I am also working closely alongside medical education platforms to ensure the delivery of content applicable to the learning of future doctors. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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