Electroconvulsive therapy (ECT) is a highly effective treatment option in treatment resistant depression (TRD). Whilst psychiatrists will prescribe it, GPs will sometimes be asked their advice by patients or their families as they are often felt to be a trusted professional who can give impartial advice on what is sometimes perceived as an intimidating procedure.

This article aims to inform on what TRD is, how ECT is used for TRD, the basic practicalities of ECT, risks and benefits, and the legal aspects of its use. It will also highlight how these issues apply in the older population where a significant complicating factor may be that of concerns over cognitive decline.



What is treatment resistant depression?

TRD is a common reason for referral to secondary mental health services and represents a significant burden to health services and patients.1 Estimates of prevalence vary dependent upon the definition used, from 55% of patients with depression in a GP population if defined as failure of one antidepressant,2 to 33% if defined as failure of two antidepressants.3 Most experts would define TRD as depression that fails to respond to at least two adequate courses of antidepressants, plus or minus a course of psychotherapy.

There are well defined guidelines described elsewhere for the initial management of depression,4 but once at least two of antidepressants have been tried, the decision on what to do next is complex and often requires secondary mental health service support. This paper aims to provide information on one possible treatment option, that of electroconvulsive therapy (ECT). There are many excellent reviews available summarising possible other options.5

What other differentials should be considered and how should they be assessed?

There are a wide range of both formal diagnoses and contributing factors that could lead to the development of depression being resistant to treatment. It is important to try to establish for each patient whether any of these are present as many of them are reversible if caught in good time. This list is not exhaustive but covers some of the general categories and most common differentials:

  • Psychiatric comorbidity: including anxiety disorders, post-traumatic stress disorder and bipolar affective disorder.
  • Cognitive diagnoses
  • Physical comorbidity: including hypothyroidism, diabetes,6 Cushing’s disease and Addison’s disease.
  • Medication side effects: including steroids and antihypertensives.7

Please see the referenced review7 for a more complete list of both physical comorbidities and medications that may contribute.

Cognitive impairment as a differential for Treatment Resistant Depression

One significant differential in the older population is that of cognitive impairment. As is well established, with increasing age comes an increased risk of dementia and mild cognitive impairment. In some individuals, the first indication of a difficulty can mimic the symptoms of depression.

An older adult may slow down in their thinking and movement, appear more anxious and less interested in their normal activities. This sometimes makes it appear that the primary issue is one of mood when in fact it can be traced back to the effects of cognitive impairment and the anxiety and distress that this can provoke.

The reverse is also true, with depression in the older patient sometimes presenting as a pseudodementia with concerns from the patient about their memory, difficulty concentrating and reduced ability to complete their normal tasks. However, in this instance, their symptoms will improve with antidepressant treatment.

Given that these two very different pathologies can present in such similar ways, specialist assessment is sometimes needed through a memory clinic, where the team will complete an extensive history, collateral history, examination, cognitive testing and sometimes functional testing, to differentiate the cause of the individual’s difficulties.

This may lead to a clearer diagnosis, but sometimes the way to resolve this dilemma may be to treat the symptoms of depression and to then reassess cognitive function when any reversible symptoms have been dealt with. This can be complicated when ECT is used as there is some evidence that it can lead to an element of cognitive impairment, specifically the loss of long-term autobiographical memory details or short-term loss around the time of the treatment. This is discussed further below.  

The use of ECT in treatment resistant depression

ECT can be a highly effective8 (and sometimes lifesaving) treatment in TRD. The evidence supporting this in the elderly is less clear,9 although it is still widely used. The NICE guidance for the use of ECT in depression is that it should be used4:

  • For acute treatment of severe depression that is life-threatening, when a rapid response is required or when other treatments have failed
  • For moderate depression only if it has not responded to multiple drug treatments and psychological treatment (this is where TRD will usually be included)
  • That repeat acute courses should only be used if it has been effective in the past, or after reviewing the adequacy of previous treatment plans, considering all other options and discussing the risk and benefits with the patient and/or advocate or carers.

There is also an emphasis on informed consent wherever possible and ongoing assessment of treatment-response and associated side effects and difficulties with this will be discussed further below.

ECT in practice

The practicalities of how ECT is delivered will vary between areas, but largely follows the same general pattern. It will start with assessment by a consultant psychiatrist to establish that this is the best treatment option. They will consent the patient for the procedure and provide a prescription as well as completing any legal paperwork that is needed.

The patient will then be reviewed by a specialist ECT team to assess their fitness for the procedure. This will usually include bloods, ECG and chest x-ray as well as baseline cognitive tests and an anaesthetic review. Whilst there are no absolute contraindications to ECT, there are many relative contraindications that make its use less safe, such as a recent heart attack or brain haemorrhage. If it is then deemed safe, they will receive treatment from either an outpatient or hospital based team, usually on a twice weekly basis.

They will be reviewed regularly to monitor the efficacy of the treatment, for any side effects such as cognitive effects and to reconfirm their ongoing consent to treatment. The standard course of treatment is twelve sessions, but this will be reviewed regularly and can be shortened or extended as required.

Although ECT is considered invasive by some, it has many benefits. It is highly effective if used appropriately, can lead to a rapid recovery and has a different side effect profile to medication-based therapy and so avoids issues including hyponatraemia, sexual side effects and gastrointestinal disturbance that are experienced with antidepressants. However, it has its own potential risks. The most important are:10

  • Anaesthetic-related including nausea, transient post-procedure amnesia. These are the same as for any brief minor surgery intervention requiring anaesthesia. The length of anaesthesia varies but is usually measured in minutes as the intervention is very brief.
  • Transient headache
  • Muscle pain
  • Dry mouth and nausea
  • Memory deficit
  • Rare but serious: cardiac or pulmonary complications
  • Historic issues: many patients will be reluctant to accept ECT because of its portrayal in the media. When first in use it lead to terrible side effects such as vertebral collapse due to muscle spasm. However, these have not been seen for many years due to the routine use of muscle relaxant during the procedure. It is also now only used for very circumscribed indications and only after either informed consent or extensive consideration under a legal framework. Patients may be reluctant to bring up these concerns, but there are many sources that they can go to for further information.

ECT and cognitive impairment

Many of the above side effects are mild and transient. However, the possibility of cognitive impairment from ECT remains a significant concern for many individuals and one that can be confusing for clinicians to explain owing to a complex available literature and a range of conflicting potential clinical factors. A recent review of this area summarises in detail the up-to-date evidence that was reviewed by a panel of experts.11

In summary, many patients experience short term problems with executive function (the ability to plan and perform complex tasks or decision making) and processing speed alongside anterograde memory (the ability to form new memories). These issues last days and resolve within weeks of the completion of treatment with no evidence of long-term deficits.

However, these conclusions are based on average results and therefore it is likely that some individuals will show improvement in these cognitive domains as a result of their depression being successfully treated, whilst others may experience a decline related to ECT or other factors. There are not enough studies that have looked at the level of individual responses to give clear advice to patients on individual percentage risks.

According to the average results available, the more persistent (and therefore significant) deficits appear to lie within retrograde memory. Subjective measures suggest that up to 40% of patients report memory loss that lasts from weeks to years. However, objective measurements suggest the rate is much lower and that the two correlate poorly.

Indeed, subjective impairment tends to reduce as an individual responds to treatment, suggesting that at least some of the difficulties are related to the underlying depression. This is an important factor to highlight as the potential cognitive risks of ECT need to be weighed against the cognitive problems caused by an unsuccessfully treated depression.

There is some evidence that certain pre-treatment factors increase the risk of significant autobiographical memory loss (retrograde memories of previous personal experiences). These include a lower baseline cognitive function, being elderly, pre-existing brain injury, lithium prescription and being female.

Figure 1 is a summary of the panel’s recommendations of what patients should be informed of and provides a balanced view of both potential risks and benefits.

Ethical and legal considerations

Given the nature of the procedure, there are extra legal safeguards placed around the use of ECT. If a patient is able to consent, they can receive ECT following a consent procedure similar to that used for surgical procedures. This can occur even if they are under the mental health act 1983 (MHA)12 if they have capacity, although different paperwork is required. However, if they lack capacity, they can either be treated under the MHA or mental capacity act (MCA).

If the MHA is used, a second opinion doctor must agree with the need for treatment, the lack of capacity and that there is not a valid advanced directive stating ECT must not be used. If the MCA is used, a best interest decision must be made, ideally with the patient involved as far as possible alongside their family and any multidisciplinary team members involved in their care.

The choice between the two frameworks can be complex and if a patient or their family needs help in understanding their legal framework and rights, they should be offered access to an independent mental health or mental capacity advocate (commonly called IMHAs or IMCAs) who can help to support them and explain the process. These individuals can also help represent the patient’s wishes at any professionals meetings.


ECT is a highly effective treatment for TRD, even in elderly populations with high levels of comorbidity or cognitive decline. Many patients report concerns with memory following the use of ECT but the reasons for this are complex due to the overlapping nature of symptoms of depression and dementia in the elderly. Whilst there is less research available than in younger patient groups, current research indicates that it is a safe treatment option even in those with dementia and that for most the effects on their memory are transient and mild.


Further information for professionals and patients






Dr Emma Pope, ST4 Older Adult Psychiatry Trainee, Devon Partnership Trust




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