Delirium Awareness and Cognitive Impairment


Published: 23 January 2018

Memory loss and confusion were once considered a normal part of ageing.

We know this is no longer the case, and older people can remain alert and capable for as long as they live. When confusion and memory problems do set in, it is important to establish whether it is part of a deteriorating condition, such as dementia, or cognitive impairment that is entirely preventable.

Someone who is cognitively impaired is at a higher risk of developing many preventable complications including falls, pressure injuries, pneumonia, urinary tract infections, functional decline and increased mortality. Because of these potential complications, they are also more likely to have prolonged hospital admissions, be readmitted or enter residential care (Australian Commission on Safety and Quality in Health Care 2018).

Despite the potential devastation it can cause, in Australian hospitals, cognitive impairment remains under-recognised and often misdiagnosed.

In patients over the age of 70, 20% of them will have dementia and 10% will have delirium. It is important to note, however, that someone with dementia can still also develop delirium. And in general medical geriatric settings, the number of older people experiencing delirium is even higher, sitting between 29-64% (ACSQHC 2018).

Many people access health services each day, and when they do, there is a need for health professionals to not only treat their prioritising health concern but also recognise and treat any other comorbidities they may have concurrently (or consequently) developed during their stay.

This article will help health workers to recognise cognitive impairment, with a particular focus on delirium and how it can be assessed and treated in health and residential care contexts.

Elderly woman with cognitive impairment | Image

What is Cognitive Impairment?

Cognitive impairment is a term used to describe someone’s current state. It generally presents as a state of confusion, loss of memory or attentiveness, trouble understanding or making sense, difficulty recognising people, places or things, or changes to mood (Health Direct 2018).

Because of the often misdiagnosed or unidentified cognitive impairment in patients, it is important to understand and differentiate between the common forms of cognitive impairment and how they can affect the individual.

Types of Cognitive Impairment

The two most common forms of cognitive impairment are dementia and delirium, with other forms including those related to a brain injury, stroke, intellectual disability or drug use (ACSQHC 2018).

It is important to remember that dementia and delirium are not a normal part of ageing, however with an ageing population, we can expect to see the number of people with these forms of cognitive impairment increasing.

Recognising Delirium

There are many similarities between dementia and delirium and they can often be mistaken for one another. Depression is also another condition that can be potentially confused with both dementia and delirium so it is important to ensure a comprehensive assessment is completed of the individual to ensure an accurate diagnosis (ACSQHC 2018).

Dementia is a progressive cognitive impairment that affects memory, judgment, language and the ability to perform everyday tasks. Delirium, however, is a treatable condition and is an acute disturbance of consciousness, attention and cognition that tends to fluctuate during the course of a day (ACSQHC 2018).

Dementia Delirium Depression
Duration Chronic condition that is progressive. Lasts hours to weeks in duration. Can last weeks to months to years.
Onset Chronic onset. Acute onset. Often abrupt onset.
Attention Generally normal attention. Impaired or fluctuating attention. Distractible but minimal impairment of attention.
Memory Recent and remote memory impairment. Recent and immediate memory impairment. Islands of intact memory.
Alertness Generally normal alertness. Fluctuates between lethargic and hyper-vigilant. Alert.
Thought Pattern May have word-finding difficulties and poor judgment. Disorganised thinking with slow or accelerated thoughts. Thinking intact but with themes of helplessness or self-depreciation.

(Agency for Clinical Innovation 2018)

It is important to note that delirium has many risk factors associated with it and will result from a complex interplay between these risk factors and their health-related events occurring.

This interplay can be demonstrated in instances such as a patient who may have pre-existing dementia, who is taking multiple medications and also has sensory impairments, who then develops acute delirium after they are given a sedative to help them sleep (ACSQHC 2013).

Delirium Causes and Risk Factors

Some of the risk factors for the development of delirium include:

  • Dementia;
  • Older age;
  • Other co-morbidities;
  • Severity of medical illness;
  • Infection (such as urinary tract infection);
  • Urinary catheterisation;
  • ‘High-risk’ medication use;
  • Diminished activities of daily living;
  • Immobility;
  • Sensory impairment;
  • Urea and electrolyte imbalance;
  • Withdrawal from alcohol or a drug;
  • Malnutrition.

(Ahmed et al. 2014)


The mnemonic MISTE is intended to help remember and group possible causes of delirium:

  • M - metabolic causes: e.g. hyponatraemia, hypoglycaemia, hypoxaemia.
  • I - infective causes: e.g. urinary tract infection, pneumonia.
  • S - structural: e.g. subarachnoid haemorrhage, urinary retention.
  • T - toxic causes: e.g. medications, drugs, poisons.
  • E - environmental: e.g. being in hospital, social isolation.

(Caplan 2011)

Elderly woman in dispair | Image

Cognitive Impairment Assessment and Screening

Because of the under-identification of people with cognitive impairment and the potential complications it can cause, it is important to perform an appropriate cognitive impairment screening and assessment.

The benefits of early screening not only alleviate concerns about cognitive impairment but if the screening is positive, it can allow steps to be taken to identify its cause and determine if it is a reversible condition, such as delirium as the result of a medication side effect. Treatment can then be commenced and further potential complications avoided (National Institute on Aging 2014).

Often, screening for cognitive impairment takes less than 10 minutes to perform. If the results are positive, a more detailed cognitive impairment assessment will need to be attended. Family members and close companions can be good sources of information about the individual when performing an assessment (National Institute on Aging 2014).

Delirium Treatment and Interventions

Management of the cognitively impaired individual should be individualised, however, most organisations will have policies and protocols to guide care.

The goal delirium management is to address its underlying cause, reduce agitation and distress, support independence and social interaction, as well as promote the safety of the patient and enable activities of daily living by involving the patient and their significant others in their care (ACSQHC 2013).

Treatment will often involve the development of a management plan, which will include reviewing the person’s current medications, as well as evaluating and implementing strategies for behavioural problems (National Institute on Aging 2014).

Some management strategies could include:

  • Ensuring a safe environment for the individual;
  • Communication strategies;
  • Orientation of the patient;
  • Preventing sleep deprivation;
  • Avoiding constipation;
  • Using sensory aids;
  • Managing pain;
  • Minimising the use of indwelling catheters;
  • Avoiding the use of physical restraints;
  • Minimising the use of psychotropic drugs;

(ACSQHC 2013)

Management of the cognitively impaired individual whilst in hospital includes identifying and managing any clinical risks such as falls, providing targeted and individualised care to the patient, engaging with carers, ensuring behaviour is managed appropriately and implementing further prevention strategies (ACSQHC 2013).

It is important to remember that whilst the individual with a new or old cognitive impairment is in hospital, they are not only dealing with their health condition, but also with a busy, noisy, unfamiliar environment. This can cause considerable amounts of distress and also exacerbate disorientation, further decreasing the patient’s independence and functional ability (ACSQHC 2013).

Note that people who have experienced delirium in the past, will be at a higher risk of developing delirium again in the future (Agency for Clinical Innovation et al. 2010).

Additional Resources


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True or False? Delirium, dementia and depression can often coexist and are risk factors for each other.

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