Delirium in older people: Symptoms, causes and treatment

Delirium is when someone’s mental function changes suddenly. It can cause confusion, agitation, altered beliefs and hallucinations. Because delirium can happen quickly, it’s important to recognise the signs early and seek urgent medical help as soon as possible.

At a glance

• Delirium definition: Delirium is a sudden state of confusion that develops over a few hours or days. It mostly affects older adults and people with dementia.

• Common triggers: Delirium often happens because of physical health problems like urinary tract or chest infections, dehydration, severe pain, or changes in medication.

• Key symptoms: Signs of delirium include sudden confusion, feeling disoriented, seeing things that are not there, big changes in sleep patterns, and shifts between being very agitated or very sleepy.

• Treatment: Unlike dementia, delirium is usually temporary. It often gets better when the underlying health problem is treated and the person is cared for in a calm, supportive setting.

What is delirium?

Delirium affects about 20% of adults admitted to UK hospitals, while care homes carry the highest risk outside hospitals. Clinically known as Acute Confusional State (ACS), delirium is a sudden change in how a person thinks and behaves.

It can happen quickly, from hours to a couple of days, and is often caused by illness or other health problems. While symptoms can vary, delirium can be extremely upsetting, not only for the person affected, but also for family and caregivers, who may feel frightened or overwhelmed.

Although anyone is at risk of delirium, it’s most common in older adults and people with dementia. The good news is that, unlike dementia, delirium usually lasts a short time and can improve once the cause is treated. Even so, it still needs quick medical care so the person can feel like themselves again as soon as possible.

What are the symptoms of delirium?

Symptoms of delirium can differ from person to person. For example, Ernie worked as a carpenter for forty years. He dedicated his life to building and fixing things until a simple urinary tract infection changed everything. Within hours, this quiet, private man became unrecognisable.

Obsessing over particular things, Ernie started to act in ways that left his son, Ian, completely unprepared. “The effect was mind-blowing,” Ian recalls. “It was like he wasn’t my dad – he was a completely different person.”

While Ernie started to obsess about things, some people suffering from delirium can become convinced people are out to get them, while others can simply be sleepy or quiet. Understanding the signs of delirium can help you support your loved one with compassion and patience. The information below can help you recognise symptoms of delirium and offer the right support.

Delirium symptoms:

• Sudden confusion: Thinking becomes cloudy quickly, making it hard to understand what’s happening.
• Difficulty concentrating: It becomes hard to pay attention, and the person is easily distracted.
• Memory problems: Short-term memory problems make it hard to remember recent events or instructions.
• Disorientation: The person may forget the time, where they are, or who people are.
• Hallucinations: They may sense things that aren’t there.
• Delusions: The person may strongly believe things that aren’t true, like thinking others are out to get them.
• Restlessness or agitation: The person may feel restless, pace, fidget, or suddenly become irritable or upset.
• Drowsiness: The person may appear unusually sluggish, lethargic, or difficult to wake up and keep engaged.
• Changes in sleep pattern: A person may be sleepy during the day, awake at night, or have their schedule completely reversed.
• Mood change: Mood can swing quickly between fear, anxiety, depression, anger, or even happiness.
• Difficulty speaking clearly: Speech can be slurred, jumbled, or slow, making it hard to communicate.

What causes delirium in older people?

Delirium usually has one or more underlying causes. Several may occur together, but the most common risk factors for developing delirium include:

• Urinary tract infections
• Chest infections
• Dehydration
• Electrolyte imbalance
• Constipation
• Pain
• Taking certain or multiple medicines
• Alcohol withdrawal
• Having surgery
• Serious illness or nearing end of life
• Poor nutrition
• Hospital admission

Delirium vs dementia: what’s the difference?

Even though the symptoms can look similar, delirium is not the same as dementia. That said, people with dementia are more likely to develop delirium, which can quickly make their symptoms much worse. The key differences between delirium and dementia are explained below.

How is delirium diagnosed?

Doctors usually diagnose delirium by looking at the person’s symptoms. They will also check the patient’s history for previous medical conditions, do a physical exam, and may order blood and urine tests to look for causes or review medications that might be making things worse. Usually, a cognitive assessment is also done.

How is delirium treated?

Treating delirium means acting quickly to identify and address the cause while ensuring the person is in a safe, calm environment. Treatment usually involves:

• Treating any infections (like chest or urinary tract infections)
• Giving fluids if someone is dehydrated
• Reviewing all medications and stopping any that could be making things worse
• Making sure pain is well managed
• Supporting good nutrition so the body can heal
• Helping the person get restful sleep
• Creating a calm, familiar environment with gentle reassurance

Medicines to reduce agitation will only be used if necessary. For example, if someone is upset or at risk of harming themselves or others. Even then, doctors would use the smallest dose for the shortest time possible, because medicines can have side effects, especially in older people.

Throughout recovery, a healthcare professional will continue to identify ongoing causes and support both the patient and their loved ones. If symptoms of delirium persist, it’s likely doctors will look again for hidden reasons and check for other conditions, such as dementia.

How long does delirium last?

For many people, symptoms usually improve after a few days, once the underlying causes have been treated. But recovery can vary. Some people may still be showing symptoms several weeks or even months after becoming unwell. This is more common in older people who have had delirium after a major operation or are already living with dementia.

Can delirium be prevented?

Delirium cannot be completely prevented, but following the guidelines below can greatly reduce its risk and severity:

• Stay hydrated
• Treat infections promptly
• Manage long-term conditions
• Keep active
• Wear hearing aids and glasses
• Maintain good sleep
• Avoid unnecessary medicines where appropriate
• Encourage orientation through clocks, calendars and familiar surroundings

Supporting someone recovering from delirium at home

When caring for someone recovering from delirium, maintaining a supportive environment is essential. Here are key steps you can take:

• Provide reassurance: Offer gentle emotional support and comfort to help the person feel safe and secure.
• Speak calmly: Use a soothing, gentle tone and simple sentences to avoid overwhelming them.
• Keep routines consistent: Maintain familiar daily schedules for meals, rest, and activities, as predictability helps reduce anxiety.
• Reduce noise and confusion: Create a peaceful space by lowering loud noises, dimming bright lights, and cutting down on extra distractions.
• Encourage eating and drinking: Give small, regular meals and offer sips of water often to help them stay well fed and hydrated.
• Watch for worsening symptoms: Keep a close eye out for any new signs of illness or discomfort and know when to get medical help.
• Attend follow-up appointments: Ensure all scheduled medical check-ins are kept to monitor recovery progress professionally.

It’s worth remembering that professional home care can offer support during recovery, giving family carers comfort and breaks.

When should you seek urgent medical help?

You should seek urgent medical help if someone experiences any of the following signs:

• Sudden confusion: Sudden changes in thinking or confusion should never be seen as “just old age” and must be checked quickly.
• Unusually sleepy or hard to wake: Trouble staying awake, low energy, or not responding needs urgent medical help.
• Hallucinations: Suddenly seeing, hearing, or feeling things that are not there.
• Becomes agitated: Being extremely restless, upset, or acting differently than usual.
• Symptoms after surgery or illness: Any sudden or worrying changes while getting better.
• Signs of stroke or severe infection: Stroke symptoms include facial drooping, arm weakness, or slurred speech (FAST symptoms). Indicators of a serious infection include high fever, chills, or rapid breathing.

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