Signs and symptoms of delirium usually begin over a few hours or a few days. They often fluctuate throughout the day, and there may be periods of no symptoms. Symptoms tend to be worse during the night when it's dark and things look less familiar. 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 switch topics
  • 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  • Being withdrawn, with little or no activity or little response to the environment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, for example, not knowing where you are or who you are
  • Difficulty speaking or recalling words
  • Rambling or nonsense speech
  • Trouble understanding speech
  • Difficulty reading or writing

Behavior changes

This may include:

  • Seeing things that don't exist (hallucinations)
  • Restlessness, agitation or combative behavior
  • Calling out, moaning or making other sounds
  • Being quiet and withdrawn — especially in older adults
  • Slowed movement or lethargy
  • Disturbed sleep habits
  • Reversal of night-day sleep-wake cycle

Emotional disturbances

This may appear as:

  • Anxiety, fear or paranoia
  • Depression
  • Irritability or anger
  • A sense of feeling elated (euphoria)
  • Apathy
  • Rapid and unpredictable mood shifts
  • Personality changes

Types of delirium

Experts have identified three types of delirium:

  • Hyperactive delirium. Probably the most easily recognized type, this may include restlessness (for example, pacing), agitation, rapid mood changes or hallucinations.
  • Hypoactive delirium. This may include inactivity or reduced motor activity, sluggishness, abnormal drowsiness or seeming to be in a daze.
  • Mixed delirium. This includes both hyperactive and hypoactive symptoms. The person may quickly switch back and forth from hyperactive to hypoactive states.

Delirium and dementia

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 ability 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 frequently 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. Your input about the person's symptoms, as well as his or her typical thinking and everyday abilities, will be important for a proper diagnosis and for finding the underlying cause.

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. Older people recovering in the hospital or living in a long-term care facility are particularly at risk of delirium.

Sept. 05, 2015