Delirium (acute confusion): a case-based approach

The case: sudden confusion overnight

Doris, 82, lives alone and is usually sharp and independent. Over one day she becomes muddled, thinks it is the wrong year, and cannot follow a conversation. She is drowsy in the afternoon but restless and frightened at night, seeing things that are not there. Her daughter is alarmed because "this isn't Mum". This rapid change, the wandering attention and the day-to-night swings are classic signs of delirium. Unlike dementia, which creeps in slowly over months or years, delirium arrives quickly and tends to come and go. Recognising that something has changed fast is the single most important clue, and it usually comes from someone who knows the person well.

What is delirium and why it happens

Delirium is a sudden disturbance of the brain's function, triggered by a physical problem elsewhere in the body. Common triggers include infection (especially urine or chest infections), dehydration, constipation, pain, low oxygen, and the side effects of medicines. Being in an unfamiliar place, poor sleep, and not having glasses or hearing aids all make it more likely. There are two main types: hyperactive delirium, where a person is agitated and restless, and hypoactive delirium, where they become quiet, sleepy and withdrawn. The quiet type is easily missed. Older people, and those with existing memory problems, frailty or serious illness, are most at risk. Delirium is a signal that the body needs urgent attention.

How the NHS assesses delirium

In hospital or at the GP surgery, staff use simple tests of attention, such as asking the person to say the months of the year backwards. Tools like the 4AT help screen for delirium quickly. The team then searches for the underlying cause with a careful history from family, a physical examination, and tests such as urine and blood tests, a chest look, and a review of every medicine. They check for pain, a full bladder and constipation, which are easy to overlook. Comparing the person's current state with how they normally are is essential, so information from relatives is gold dust. Finding and treating the trigger is what turns delirium around, so the search is thorough.

Keeping the person safe and calm

While the cause is treated, care focuses on comfort and orientation. Staff reintroduce themselves, explain clearly, and keep a calm, well-lit environment with a visible clock and calendar. Glasses and hearing aids are put back in. Familiar faces, photos and gentle reassurance help enormously, so family visits are encouraged. Good sleep, regular drinks, food and mobilising all support recovery. Medicines to sedate are used only as a last resort and briefly, because they can make delirium worse. Physical restraint is avoided. The approach is patient and human: reduce fear, reduce noise, meet basic needs, and give the brain the best chance to settle as the physical illness improves.

Recovery and what families can do

Many people improve within days once the cause is treated, but some take weeks, and older or frailer people may not fully return to their previous selves. Delirium can be frightening, and afterwards people may recall distressing dreams or feel low, so it helps to talk it through gently. Families can support recovery by visiting, bringing familiar objects, encouraging drinks and gentle activity, and flagging any new confusion early. Because an episode of delirium can be an early sign of future memory problems, a follow-up with the GP is sensible. Preventing further episodes means treating infections promptly, staying hydrated, managing constipation and reviewing medicines regularly.