Sudden confusion in older people: when it may not be dementia

When an older person suddenly becomes confused, it is easy to assume it is dementia. But confusion that comes on over hours or days is often caused by something else, and it needs checking quickly.

What is delirium?

Delirium is a sudden change in a person’s mental state. They may become confused, drowsy, agitated or restless, see things that are not there, or struggle to concentrate. It often changes through the day and can be worse at night.

People with dementia are more likely to get delirium, and it can be hard to spot. The key sign is a sudden change from how the person usually is.

Common causes

• An infection, such as a urine infection or a chest infection
• Not drinking enough (dehydration)
• Constipation
• Pain
• A high temperature
• Starting or stopping a medicine, or the side effects of a medicine
• Low blood sugar
• After an operation or an illness

What to do

If someone becomes confused suddenly, get medical advice the same day. Contact their GP or call NHS 111. Call 999 if they are very unwell, for example if they are drowsy and hard to wake, or have signs of a stroke.

Delirium usually improves once the cause is treated, although it can take days or weeks.

Depression can also look like dementia

An older person with depression may be agitated, sleep badly and struggle to think clearly. Depression is common in later life and can be treated, so it is worth talking to the GP. Sometimes a person has both depression and dementia, and the depression should still be treated.

How a care home helps

Care staff who know a resident well are often the first to notice a sudden change. The guide for carers written by Christian Care Homes says the same: when someone who is usually alert suddenly becomes confused, look for a cause such as a urine infection or a side effect of medication, and ask the GP for advice. Read the full guide, What is dementia?.