July 2024

The Differences between Delirium and Dementia – delete

Many people are more familiar with dementia than delirium and often do not understand the difference between them. Before this module gets into detail on the topic of delirium, it is best to differentiate delirium and dementia right away.

Delirium is a term that describes a new, sudden change in a person’s ability to think, remember and understand what is going on around them. A person who is delirious may appear confused, disorganized, hyper, frightened, forgetful, and suspicious of other people. In a delirium, people also commonly hallucinate (e.g. tell you that they see people/objects/animals that are not there).

Delirium is typically caused by something else going on in the body (e.g. infection, withdrawal, sleep deprivation, severe pain, shock, etc.). Delirium typically can be treated as long as the cause of the delirium is determined quickly and treated properly (e.g. taking antibiotics for an infection).

Dementia is a term thatdescribes changes to a person’s ability to independently interact with the world as a result of changes happening in their brain. The brain is the powerhouse driving a person’s ability to interact with the world around them. A person’s abilities may be altered or weakened, depending on where in the brain changes are occurring. The result may be that a person becomes dependent on others for day to day routine tasks to stay safe. Dementia can result in changes to memory, language ability, social skills, driving, and finances. These changes start to show slowly and do not happen overnight. There are many types of dementia; dementia of the Alzheimer type is the most common.

What are the differences between delirium and dementia? Now that you have had an introduction to both delirium and dementia, you can begin to see the differences between them. Below is a simple table that describes the most common differences between delirium and dementia.

comes on very quickly (within hours or days)a change in mental status, or sudden onset of confusioncaused by something else going on in the body (e.g. dehydration, infection, shock, sleep deprivation, etc.)often the person can go back to being themselves if the cause is determined and treateddevelops slowly (over months or years)changes to a person’s ability to interact with the world around them independentlycaused by changes to different areas of the brainalthough the symptoms can be slowed down in some cases, typically the person cannot return to normal functioningis irreversible

Activity 6.1

Test Yourself

Match each statement to the correct topic to see if you can spot the difference between delirium and dementia.

Common Risk Factors for Delirium

Although there are many different and unique causes and risk factors for developing delirium, the following list highlights some of the most common:

  • alcohol or other substance use disorders
  • change of environment (hospital stay, new living arrangement)
  • constipation
  • dehydration
  • diagnosis of dementia
  • infections
  • over stimulation (e.g. too much noise, activity, or too many people from the usual)
  • poor nutrition
  • some medications
  • organs (pancreas, liver, lungs, etc.) are not functioning normally
  • vision or hearing impairment

Recognizing Delirium

Delirium is complicated and is experienced differently by each person. This is one of the reasons that delirium is so hard to recognize. The following table will help you understand what delirium often looks like.

Delirium: Common Signs and Symptoms

What is NewWhat You May NoticeExample
Sudden Change in Thinking and Behavioursuddenly, the person you care for is thinking and behaving very different from their usual selfunpredictable mood changes from one moment to the nextpersonality and behaviour of the person you are caring for changes unlike anything you have ever seen in them beforean active person sleeping all day longa quiet person yelling out and unable to settle downan independent person all of a sudden unable to get their daily tasks done (e.g. bathing, dressing, cooking, feeding their pets, taking their medications)
Difficulty Concentratingthe person is not able to focusmay be distracted by sounds or moving objectsdarting their eyes from place to placerestlessunable to follow along in conversation
Disorganized Thinkingthey have difficulty answering a simple question because they seem confused.the answer they give you does not make any sense.what they are talking about is very unorganized.they may answer you by talking about something completely different to the subjectthey may speak in a very bizarre way about unrelated topics.they may tell you that people are trying to harm them or they may be fearful of you.for example, when asked to count backwards from 100, John said “100, 99, …where’s Mary? I’ve got to pick up the kids, where’s Mary?!
Poor Memorya person suddenly is very forgetfula person may have difficulty remembering what their address is, the date, the year, the town they live in.they may have difficulty remembering a conversation just minutes or hours before.a person may not remember how and when to take medications or how to make their usual breakfast.
Altered Level of Consciousnessa person is not as alert as their usual selfa person can appear highly hyper and excitable, unable to settle down or sleep, and restless.a person may also appear very drowsy and sleep for many more hours than their usual self.a person may appear as though they are falling asleep during a conversation with them
HallucinationsA person may tell you that they see, feel, or hear things, people, and objects that are not there.they may tell you that they see animals in the room, bugs on their clothes, people standing near them, etc.they may hear music playing in the room that is not really playing
Moments of ClarityA person experiences times of confusion and other times of clarity in the same day.in the course of a day, a person may be their usual self and suddenly their conversation or actions are completely different to their usual behaviour

Activity 6.2

Try a Tool

If you are noticing any of the common signs and symptoms of delirium in the table above, take a moment to complete the Delirium Detection Questionnaire for caregivers. This is a tool that will assist you in speaking with a health care professional about the changes you are noticing and determine the next course of action. Try completing the Delirium Detection Questionnaire.

Diagnosing Delirium

As a caregiver, you may notice a sudden change, and/or signs and symptoms of delirium, before anyone else. This is often because you may have known the person for a very long time and would be aware of their usual behaviours and if there were any subtle changes in them. Your recognition is the first step to receiving a diagnosis. The formal diagnosis of delirium comes from a health care professional. Diagnosis is important and is often the first step to determining cause and treatment. In order to receive a diagnosis of delirium, consider the following:

  • if possible, visit a health care professional that already has a trusted relationship with you and the person you are caring for (e.g. family doctor or nurse practitioner)
  • this professional will review the details of the sudden changes, the signs and symptoms you are noticing, and may want to perform tests to determine the cause of this change (e.g. a blood test to look for infection)
  • once the cause is determined, treatment can begin and the delirium will clear, allowing the person to go back to thinking and behaving like their usual self

Activity 6.3


Canadian hospital takes action to prevent delirium (6:37) from CBC’s The National will help you understand more about how a person may experience delirium and a program that some hospitals have adopted to prevent delirium.