Basic Facts

Delirium is a problem that needs quick treatment by a healthcare professional because it can cause death, disability, cognitive (thinking and memory) problems, and entry into a nursing home.

A sudden change in an older adult’s mental abilities is a sign of delirium, which is a serious health problem. This condition needs the attention of a healthcare professional. Healthcare professionals don't recognize delirium in up to half of people who have it.

Who is at Risk of Delirium?

Delirium happens often among older adults. This risk increases with:

  • Surgery. Up to half of people having high risk surgery (for example, repairing a broken hip) have delirium.
  • Use of hospitals or nursing homes. One-third of those age 70 and older who are in the hospital experience delirium. Up to 15 percent of people entering a skilled nursing home have delirium.
  • Pre-existing dementia or cognitive impairment.
  • Age. Up to 15 percent of older adults who come to emergency departments have delirium. 
  • End of life. Up to 85 percent of people have delirium when they are dying. 

Types of Delirium

Delirium usually has three forms:

  1. A hyperactive form, when people feel stressed, excited or very alert.
  2. A hypoactive form when people have low energy, are sleepy, move less than normal, or aren’t aware of what is going on. 
  3. A mixed form when people switch between hyperactive and hypoactive forms. Sometimes a person with delirium may switch between having low energy and being excitable within a single day.


Often, workers don’t know that an older adult has delirium because they become less active (hypoactive), rather than more restless (hyperactive). The hypoactive (“quiet”) form of delirium happens in up to 75 percent of people with the condition. Healthcare providers may assume that hypoactive delirium is depression.


Last Updated May 2023

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