What is delirium?

Delirium is a sudden, usually reversible state of confusion caused by illness, infection, medication or surgery, and it is not the same as dementia. MedlinePlus notes that symptoms usually start suddenly, over a few hours or a few days, and attention tends to come and go through the day. In older adults, urinary tract infections, dehydration, pain and new medications are common triggers.

Delirium is caused by an underlying medical problem that disrupts how the brain works. MedlinePlus lists infections such as urinary tract infections, pneumonia and the flu, medicines, surgery and reactions to anesthesia, dehydration, severe pain, sleep deprivation, and alcohol or drug intoxication or withdrawal. Having dementia, being in a hospital and older age all raise the risk. Sudden confusion should be checked by a doctor promptly.

No. Delirium comes on suddenly, over hours or days, is usually caused by an illness or medication, and often clears once the cause is treated. Dementia develops slowly over months or years and is a lasting decline in memory and thinking. The two can overlap: people with dementia are far more likely to develop delirium, and it is often mistaken for the dementia getting worse.

Delirium can often be reversed once its cause is found and treated, for example by treating an infection, correcting dehydration or changing a medication. While that happens, MedlinePlus describes keeping the room quiet and well lit, keeping clocks and calendars in view, having family nearby, and making sure the person has their glasses and hearing aids. A doctor should guide treatment.

Yes. Sudden confusion should be treated as a medical emergency, because delirium signals an underlying problem, such as an infection or a reaction to a medication, that needs prompt care. Treating that cause can return the person to how they were the week before. If someone with or without dementia becomes suddenly confused, contact their doctor right away or seek urgent care.