The signs and symptoms of delirium appear over a short period of time, from a few hours to a few days. They often fluctuate throughout the day, so a person may have periods of no symptoms. Primary signs and symptoms include those below.
Reduced awareness of the environment
This may result in:
- An inability to stay focused on a topic or to change topics
- Wandering attention
- Getting stuck on an idea rather than responding to questions or conversation
- Being easily distracted by unimportant things
- Being withdrawn, with little or no activity or little response to the environment
Poor thinking skills (cognitive impairment)
This may appear as:
- Poor memory, particularly of recent events
- Disorientation, or not knowing where one is, who one is or what time of day it is
- Difficulty speaking or recalling words
- Rambling or nonsense speech
- Difficulty understanding speech
- Difficulty reading or writing
- Seeing things that don't exist (hallucinations)
- Restlessness, agitation, irritability or combative behavior
- Disturbed sleep habits
- Extreme emotions, such as fear, anxiety, anger or depression
Delirium and dementia
Other medical conditions can result in symptoms associated with delirium. Dementia and delirium may be particularly difficult to distinguish, and a person may have both. In fact, frequently delirium occurs in people with dementia.
Dementia is the progressive decline of memory and other thinking skills due to the gradual dysfunction and loss of brain cells. The most common cause of dementia is Alzheimer's disease.
Some differences between the symptoms of delirium and dementia include:
- Onset. The onset of delirium occurs within a short time, while dementia usually begins with relatively minor symptoms that gradually worsen over time.
- Attention. The inability to stay focused or maintain attention is significantly impaired with delirium. A person in the early stages of dementia remains generally alert.
- Fluctuation. The appearance of delirium symptoms can fluctuate significantly and often throughout the day. While people with dementia have better and worse times of day, their memory and thinking skills stay at a fairly constant level during the course of a day.
When to see a doctor
If a relative, friend or someone in your care shows any signs or symptoms of delirium, see a doctor. If the person has dementia, be aware of relatively sudden changes in overall awareness and engagement, which may signal delirium. Your input about the person's symptoms, as well as his or her typical thinking and everyday abilities, will be important for a diagnosis.
Older people recovering in the hospital or living in a long-term care facility are particularly at risk of delirium. Because symptoms can fluctuate and some symptoms are "quiet" — such as social withdrawal or poor responsiveness — delirium may be missed. If you notice signs and symptoms of delirium in a person in a hospital or nursing home, report your concerns to the nursing staff or doctor rather than assuming that those problems have been observed.