What Is Delirium? - Definition, Causes & Treatment

What Is Delirium? - Definition, Causes & Treatment
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  • 0:07 Delirium
  • 1:10 Diagnosis
  • 2:53 Delerium or Dementia
  • 4:02 Causes and Treatment
  • 5:54 Lesson Summary
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Lesson Transcript
Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

What does it mean to be delirious? What might cause someone to be confused and disoriented, and what can be done to treat it? In this lesson, we'll look at the symptoms, causes, and treatment of delirium.


Charlotte is in the hospital because she fell and had to have hip replacement surgery. Her granddaughter Mimi comes to visit her often, and soon Mimi notices a strange pattern. When she visits Charlotte in the morning, she seems OK. She talks and acts normally, though sometimes she gazes off into space and seems to get lost in her own thoughts. But overall, Charlotte seems fine in the mornings.

But when Mimi comes to visit in the afternoons or evenings, something is different. Charlotte seems confused and sometimes doesn't know what day it is or where she is. Her attention wanders, and she doesn't always seem to be aware that Mimi is there.

The doctors who check in on Charlotte usually do their rounds in the morning, so they don't ever see her at her worst. But Mimi is concerned. She heard in her psychology class at school that some people suffer from delirium, a cognitive disorder that involves confusion and disorientation, among other symptoms. Could Charlotte have delirium?


Imagine that you are a psychiatrist, and Mimi asks you to visit Charlotte in the evening, when she's at her worst. When you arrive, you see some symptoms of delirium. In order to diagnose Charlotte, you go down a checklist of the criteria for delirium.

1. Less attention to the environment and less ability to focus attention. Charlotte's attention drifts off, and she seems in her own world. She definitely fits this criterion.

2. A change in thinking or perceiving that's not explained by another condition. Charlotte has a hard time coming up with the right words to express herself, and sometimes has a hard time understanding others. These are examples of cognitive difficulties that go along with delirium.

Occasionally, patients will also see things, or hallucinate. Though Charlotte isn't hallucinating, she has lost cognitive functioning, and there's not another psychological condition, like dementia, that could explain it.

3. The symptoms develop quickly and fluctuate during the day. Charlotte's delirium came on over a few days, and she's usually better in the morning than the evening, so you can check this one off.

4. There is evidence that it is caused by a medical condition. When you examine Charlotte, you notice that she has developed an infection after her hip surgery. The delirium might be caused by that.

Because Charlotte meets all four criteria, you can diagnose her with delirium.

Delirium or Dementia?

Delirium is sometimes confused with dementia, another cognitive disorder that involves losing the ability to think clearly and losing memories. Because delirium and dementia are so similar, someone with delirium can be diagnosed with dementia and vice versa. But there are a few key differences.

1. Onset of the condition. Delirium usually develops quickly, within a few days, while dementia develops slowly over months or years.

2. Attention. Someone with delirium often has problems engaging or disengaging their attention. As a result, they often come across as 'out of it.' In contrast, patients in the early stages of dementia are usually alert.

3. Fluctuation. While dementia patients are usually the same no matter when you talk to them, delirium patients' symptoms fluctuate during the day. Sundowning, or worsening of symptoms as night sets in, is common for delirium patients.

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