Signs of Delirium in Dementia

How to Spot Signs of Delirium in Someone With Dementia
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Delirium is a state of acute mental confusion, meaning a person's state of mind suddenly becomes worse than usual. For someone with dementia, what's "usual" may already be considerable memory loss and confusion, but when the person becomes delirious, you can often tell that the mental impairment has taken a sudden turn for the worse. The change usually happens over a period of hours but sometimes comes on more gradually (over days).

Delirium's rapid changes in brain function are usually caused by a stress, such as an illness, that's affecting the body overall. In an older adult, delirium can be the only outward sign of a life-threatening illness, so it's essential for caregivers to learn to recognize delirium and then get help promptly. Delirium also predisposes a person with dementia to acceleration of memory loss, another reason a quick response is important.

The signs of delirium vary from person to person. There's no single way someone acts delirious. So trust your intuition. When a caregiver senses something's "off" about a loved one's behavior or functioning, there's often a very real reason for it.

Here are the most common signs of delirium:

A change from usual mental functioning.

A change in mental functioning is the main sign of delirium, which can take a variety of forms depending on the individual. The change comes on quickly -- in a matter of hours (although sometimes the decline takes place over a few days).

Confused thinking

The person seems more disoriented to time and location than usual. He or she may be oblivious or mistaken about the time of day, the year, or where you all are. (Again, look for a change from the person with dementia's normal awareness of these things.)

Difficulty paying attention

The person has trouble focusing (on conversation, on anything).

Agitation, being more revved up than usual

This can range from a surge in nervous energy to increased combativeness or anger. Someone who's usually mild-mannered may behave aggressively.

Quieter or drowsier

Although "being delirious" tends to call up images of raving madness, in many people delirium manifests as becoming quieter and more spaced out. This is called hypoactive delirium, and although it's certainly easier on caregivers and hospital staff, it still needs to be recognized and evaluated, since hypoactive delirium, like all delirium, can be a sign of life-threatening illness.


The person doesn't act like his or her usual self. He or she may see or hear things that aren't real, make false accusations, or otherwise not be grounded in reality. In someone with dementia who has been having hallucinations or delusions already, they may be more frequent or troubling.

Fluctuating confusion

A tricky aspect of delirium is that the mental changes often fluctuate throughout the day, so the person may alternate between seeming fine at times and seeming much more confused than usual at other times.

For dementia caregivers, the challenge is that you may have already noticed that your loved one tends to have good days and bad days, or good and bad times of day. So how can you identify changes associated with delirium? The problem is similar to that of parents trying to assess whether a child is truly sick versus just having a fussy day. Look for patterns in a typical day -- for example, many people with dementia ordinarily have better mornings than late afternoons. In that case, extra confusion that appears in the morning might be a red flag.

Once you notice the first possible signs of delirium, pay even closer attention to possible other changes over the next hours and days.

Note: It's especially hard to detect delirium in people with Lewy body dementia. That's because this type of dementia, which is often associated with Parkinson's disease, involves fluctuating mental states.

Learn what to do if you suspect your loved one may be showing signs of delirium.

Learn about causes of delirium.