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Dear Mayo Clinic:
My mother is 78, and over the past two weeks, she has become really confused off and on. Before this, she seemed fine, other than having some problems with short-term memory loss.
Could this be delirium? How is delirium different from the beginnings of dementia?

A: It is possible that your mother has delirium, which is a common condition that occurs when people become ill. It also can be a side effect of some medications.

Unlike dementia, which develops gradually over a long period of time, the start of delirium usually is rapid. Symptoms of delirium require prompt medical evaluation to determine the underlying cause and start treatment.

Symptoms of delirium

Signs and symptoms of delirium usually begin over the course of a few hours or a few days.

Delirium is a serious disturbance in mental abilities. Its hallmarks include changes in attention, such as becoming extremely confused or withdrawn, and having that condition shift throughout the day. For example, some people affected by delirium will be fine in the morning and then become confused at night.

Other symptoms of delirium may include restlessness, agitation, hallucinations, anxiety and unpredictable mood changes, as well as sleep problems, sluggishness and abnormal drowsiness.

Delirium often is triggered by an acute illness, such as an infection or a condition that affects the body’s metabolism, like low sodium or low calcium.

Delirium also can be caused by heart or lung problems, such as chronic obstructive pulmonary disease, a pulmonary embolism or a heart attack.

Many medications can cause delirium when they are first introduced. Those most frequently associated with delirium include some types of medication prescribed for pain, sleep problems, mood disorders, allergies, asthma, Parkinson’s disease and spasms or convulsions.

How it differs from dementia

It sometimes can be hard to tell the difference between delirium and dementia, but there are several distinguishing factors. The most obvious is the onset of these disorders, with delirium developing quickly and dementia developing slowly.

In addition, dementia often begins with memory loss that involves daily activities, such as forgetting appointments or bills, or having difficulty with planning.

Unlike those affected by delirium, people with early-stage dementia typically don’t have problems with their ability to maintain attention, and they generally remain alert and engaged with what’s going on around them.

Finally, symptoms of dementia don’t fluctuate as much as those of delirium. People who have dementia may have times of the day that their symptoms seem somewhat better or worse. But, overall, their memory and thinking skills stay fairly constant throughout the day.

It is possible to have both dementia and delirium. Delirium frequently occurs in people with dementia. But having episodes of delirium does not always mean a person has dementia.

In a situation like your mother’s, where a family member or friend notices symptoms of delirium, it’s important that the affected individual receive a medical evaluation.

Delirium usually can be diagnosed based on a person’s medical history and symptoms, along with tests to assess mental status and identify underlying health problems. Input from a family member or friend during the evaluation often helps the healthcare provider arrive at an accurate diagnosis.

If a new health concern is uncovered during the medical assessment, treatment for that condition often relieves delirium symptoms.

When delirium is caused by medications, adjusting the dose or switching to an alternative medication may be all that’s needed to eliminate delirium.

— Paul Takahashi, M.D., Community Internal Medicine, Mayo Clinic, Rochester, Minn.

Mayo Clinic Q & A is an educational resource and doesn’t replace regular medical care.
Email a question to MayoClinicQ&A@mayo.edu. For more information, visit www.mayoclinic.org.