Clinical Review: Delirium

The term 'delirium' was first used as early as the first century AD to describe mental disorders occurring as a consequence of fever or trauma to the head.(1)

A detailed clinical history is important in recognising episodes of delirium (iSTOCK)
A detailed clinical history is important in recognising episodes of delirium (iSTOCK)

Section 1 Epidemiology and aetiology

In the present day, delirium is also known by the more descriptive term 'acute confusion'. It describes the sudden onset of mental confusion, accompanied by a degree of disturbed consciousness, cognitive function and/or perception.

The condition develops over 24-48 hours and is commonly associated with a reversible medical, surgical or pharmacological insult to the body.2

Delirium can present as hyperor hypoactive. In the former, the patient may be agitated or even aggressive, while in the latter, they may be withdrawn and drowsy.

It is possible for delirium to present as a mixture of the two states; this can be difficult to diagnose and often leads to delays in management.

According to NICE guidelines,2 in the UK, about 20-30% of medical inpatients will develop delirium during their admission, while the same is true of 10-50% of surgical inpatients.

The clinical and social outcomes of delirium are poor if management is not addressed early on in its evolution. This can also have an adverse economic impact.

Section 2 Making the diagnosis

Recognition of delirium requires brief cognitive screening and clinical observation. In all of the three subtypes - hyperactive, hypoactive and mixed - the following domains may be affected:

  • Consciousness
  • Orientation
  • Memory
  • Thought
  • Perception
  • Behaviour

Patients with the hyperactive subtype of delirium may experience restlessness, agitation, hypervigilance, thought disorder and perceptual abnormalities. Those with the hypoactive subtype may be lethargic and sedated, and may demonstrate psychomotor retardation.

Standard diagnostic criteria are given in DSM-5, the fifth edition of the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders,3 and ICD-10, the WHO Classification of Mental and Behavioural Disorders.4

Another important factor to consider when making a diagnosis is whether the patient is presenting with a picture of acute or chronic confusion, or acute-on-chronic.

The clinical history is of vital importance in answering this question. Factors to consider include:

History and time course - was the onset sudden or gradual? Has it lasted days or longer? Have there been similar episodes in the past?

Cognition against a baseline - what was cognition like before this episode? Consider using formal cognitive tests or, if short of time, brief assessment of orientation and attention (a digit span or serial sevens subtraction test).

Fluctuations in consciousness/cognition/sleep - are deficits consistent over time, or transient and changeable?

Potential causes - have there been any recent physical insults (commonly, infections or orthopaedic procedures), complications or changes in medication?5 Withdrawal from benzodiazepines or alcohol can precipitate delirium.

Symptoms that are of sudden onset, quickly progressing, fluctuating and temporally associated with a physical insult suggest a delirium-type picture. The most commonly used instrument for the identification of delirium is the confusion assessment method (see box 1).6, 7

Section 3 Managing the condition

Effective communication with the patient, their family8 and colleagues in the multidisciplinary team is the key to effective management of patients with delirium.

This is especially true if the patient presents as anxious or distressed. Calm verbal de-escalation should always be a first-line intervention in these scenarios.

If a diagnosis of delirium has been established and a cause identified, management should focus on treating the cause. Further management options can be divided into non-pharmacological and pharmacological interventions.


Non-pharmacological interventions should be tried first and should include efforts to orientate the patient in time and place.

These can include:

  • Establishing physiological stability: adequate oxygenation, restore electrolyte imbalance, restore hydration
  • Optimising the environment: avoid sensory deprivation and overload, minimise noise, optimise lighting, provide familiar objects
  • Addressing modifiable risk factors: manage pain, correct sensory deficits, support normal sleep pattern
  • Optimising communication: calm, supportive approach, avoid confrontation, reorientation (try using a clock or calendar), staff consistency, involve the patient's friends or family
  • Reviewing medication: if medication is deemed necessary, consider the lowest effective therapeutic dose
  • Mobilisation
  • Structured routine
  • Encouraging self-care

A behavioural chart (also known as an Antecedent, Behaviour, Consequence, or ABC, chart) can be useful in determining specific triggers for agitation and can help to shape practical management.


There is little robust evidence for the use of pharmacological interventions for delirium.5 Pharmacological methods should only be used if non-pharmacological methods have failed and there is concern regarding risk to the patient or others secondary to agitation or aggression.2

A low dose of an antipsychotic, such as haloperidol or olanzapine, can be considered. Haloperidol is a high-potency medication, with relatively few anticholinergic side-effects and a wide range of doses and routes of administration.

Patients should be commenced on 0.25-0.5mg orally in the first instance. In patients with MS, Lewy body dementia or Parkinson's disease, haloperidol is best avoided, owing to the risk of severe extrapyramidal side-effects. In these patients, quetiapine 12.5mg could be considered.

Benzodiazepines are best avoided if possible, owing to their propensity for worsening confusion. However, they may be considered if antipsychotics are contraindicated, or in situations where the delirium is due to alcohol or benzodiazepine withdrawal.

The following are important points to consider with pharmacological interventions for patients with delirium:

  • Psychotropics should be reserved for patients exhibiting symptoms of agitation or psychosis
  • In the absence of psychotic symptoms, treating hypoactive delirium with psychotropics is not recommended
  • Psychotropics are not indicated for wandering
  • Always consider monotherapy, and use the lowest possible dose of these medications

Section 4 Prognosis

Studies have suggested that symptoms of delirium can persist after discharge in up to 51% of patients.9,10 This can lead to impaired function.

It is now evident that delirium is also associated with brain injury, because delirium is a strong risk factor for new-onset dementia,11 as well as acceleration of existing dementia.12

This highlights the importance of prompt diagnosis and management of patients with the condition, to lower the risk of any long-term complications.13

Section 5 Case study

Margaret is a 75-year-old patient with a diagnosis of mixed Alzheimer's disease and vascular dementia. She lives in a residential home.

Over the past three to four days, the staff at the home have reported that Margaret has become increasingly confused and agitated, and has been hitting staff when they try to move her for a wash or at dinnertime.

She seems to be having periods in which she is drowsy and quite non-responsive and then is quite lucid again, although disorientated.

The staff thought this might be progression of her dementia and contacted the local community memory service for a review of her dementia medication.

On review by the team, it becomes apparent that the onset of her confusion and aggression was quite acute and has been progressively worsening over the past three days.

Consider causes

A couple of days before Margaret's symptoms started, it was noted by a member of staff at the home that her right leg was slightly red and swollen, although at the time, Margaret denied any tenderness in her leg.

On examination, her leg was very swollen, red and tender to touch. She was tachycardic and her BP was low. Blood tests showed raised inflammatory markers and electrolytes.

A diagnosis was made of delirium secondary to right leg cellulitis and subsequent dehydration due to poor fluid intake.

Margaret was admitted to a medical ward for IV flucloxacillin and rehydration. After a few days of treatment, the cellulitic infection resolved and Margaret's delirium improved; she became more settled and her cognitive level returned to its baseline.

Section 6 Evidence base


Key texts

  • American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (fifth edition). Washington, DC, American Psychiatric Association, 2013.
  • WHO. The ICD-10 Classification of Mental and Behavioural Disorders: Diagnostic Criteria for Research. Geneva, WHO, 1993.

Contributed by Dr Reshad Malik, academic clinical fellow in old age psychiatry, UCL Institute of Neurology, London, and Dr Muffazal Rawala, consultant liaison psychiatrist, Luton and Dunstable Hospital, Luton.


These further action points may allow you to earn more credits by increasing the time spent and the impact achieved.

  • Have a discussion with colleagues and the practice team about non-pharmacological interventions in patients presenting with delirium, to enhance understanding of the condition.
  • Write a protocol for use of pharmacological treatments in delirium.
  • Organise a clinical meeting with a psychiatric consultant colleague to discuss the management of patients with delirium.

Click here to take a test on this article and claim a certificate on MIMS Learning


1. Chadwick J, Mann MN. The Medical Works of Hippocrates. Oxford, Blackwell, 1950.

2. NICE. Delirium: diagnosis, prevention and management. CG103. London, NICE, July 2010.

3. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (fifth edition). Washington, DC, American Psychiatric Association, 2013.

4. WHO. The ICD-10 Classification of Mental and Behavioural Disorders: Diagnostic Criteria for Research. Geneva, WHO, 1993.

5. Inouye SK, Westendorp RGJ, Saczynski JS. Delirium in elderly people. Lancet 2014; 383: 911-22.

6. O'Mahony R, Murthy L, Akunne A et al. Guideline Development Group. Synopsis of the National Institute for Health and Clinical Excellence guideline for prevention of delirium. Ann Intern Med 2011; 154: 746-51.

7. Inouye SK, van Dyck CH, Alessi CA et al. Clarifying confusion: the confusion assessment method: a new method for detection of delirium. Ann Intern Med 1990; 113: 941-8.

8. Morandi A, Davis D, Taylor JK et al. Consensus and variations in opinions on delirium care: a survey of European delirium specialists. Int Psychogeriatr 2013; 1-9.

9. Cole MG. Persistent delirium in older hospital patients. Curr Opin Psychiatry 2010; 23: 250-4.

10. Dasgupta M, Hillier LM. Factors associated with prolonged delirium: a systematic review. Int Psychogeriatr 2010: 373-94.

11. Davis DH, Muniz Terrera G, Keage H et al. Delirium is a strong risk factor for dementia in the oldest-old: a population-based cohort study. Brain 2012; 135: 2809-16.

12. Fong TG, Jones RN, Shi P et al. Delirium accelerates cognitive decline in Alzheimer disease. Neurology 2009; 72: 1570-5.

13. Maclullich AMJ, Anand A, Davis DH et al. New horizons in the pathogenesis, assessment and management of delirium. Age Ageing 2013: 667-74.

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