Delirium

Symptoms and key features

• trouble focusing, following a conversation, or keeping track of a question
• confusion about where they are, what day it is, or why they're there
• symptoms that swing over hours, clear in the morning and much worse by evening
• a change in alertness, either agitated and restless or unusually sleepy and withdrawn
• disturbed sleep, often awake at night and drowsy in the day
• seeing or hearing things that aren't there, or firm false beliefs, often frightening ones
• rambling or disorganized speech

What it looks like

A 79-year-old man has hip surgery. He was sharp before the operation. Two days later he's pulling at his IV, insisting the nurses are strangers who've kidnapped him, and doesn't recognize his daughter at 11 p.m. By the next morning he's calm and polite and remembers little of the night.

That swing is the signature. Delirium comes on over hours to days, and it moves. Families often see it before staff do, because they know how the person usually talks.

The quiet version is easy to miss. Hypoactive delirium looks like someone who's just tired: lying still, answering in single words, eating little. It's common in older adults and often gets mistaken for depression or plain exhaustion. It carries the same risks as the agitated kind.

What people often confuse this with

Dementia. Dementia develops over months to years, and attention usually holds up until later stages. Delirium starts over hours or days and attention is one of the first things to go. The two overlap often: dementia is one of the biggest risk factors for delirium, and a person with dementia who suddenly gets worse may have delirium on top. See a medical clinician for that sudden change.

A psychiatric illness. Hallucinations and paranoia can look like schizophrenia or mania. A first episode of psychosis in someone over 60, especially with confusion or drowsiness, should be treated as a medical problem until proven otherwise.

Depression. Quiet, hypoactive delirium can look like low mood. Depression doesn't usually cause fluctuating attention or disorientation.

"Just old age" or "sundowning." Getting confused in the evening isn't a normal part of aging. A new pattern deserves a look.

What research says

• Prevention works. A 2015 meta-analysis in JAMA Internal Medicine pooled 14 studies of multicomponent, non-drug programs. Delirium incidence fell (odds ratio 0.47), and falls fell too.
• Drugs don't prevent or cure it reliably. A 2014 Lancet review60688-1) by Inouye and colleagues concluded there's no convincing evidence that drug prevention or treatment is effective, and that cutting sedating and pain drugs where possible and using non-drug approaches are the recommended strategy.
• It's serious. The same review describes delirium as common, costly, under-recognized, and often fatal in older adults. It's linked to longer hospital stays, falls, and moves into long-term care.
• It may leave a mark. Researchers think delirium may be both a sign of a vulnerable brain and a possible cause of lasting cognitive decline. That question isn't settled.

How it's diagnosed

There's no blood test for delirium itself. A clinician diagnoses it at the bedside by checking attention and comparing the person to how they were before. The DSM-5-TR criteria describe a disturbance in attention and awareness that develops over a short period, fluctuates, and comes with another change in thinking, and that's caused by a medical condition, a substance, or withdrawal.

Short screening tools help. The CAM (Confusion Assessment Method) and the 4AT are used on hospital wards to check for acute onset, fluctuation, inattention, and disorganized thinking. Asking the family "Is this how they normally are?" is one of the most useful questions in medicine.

The diagnosis is only half the job. The other half is finding the cause, which usually means:

• a review of every medication, especially new ones, sedatives, sleep aids, opioids, and drugs with anticholinergic effects
• a check for infection, including urine, chest, and skin
• blood tests for sodium, glucose, kidney and liver function, and blood counts
• looking for pain, constipation, urinary retention, low oxygen, or dehydration
• asking about alcohol or sedative use, since withdrawal can cause delirium
• brain imaging when there's a fall, a head injury, or a new neurological sign

Often there's more than one cause at once.

Why it happens

Delirium is the brain's response to physical stress. The more vulnerable the brain, the smaller the trigger needed to tip it over. Vulnerability includes older age, dementia or other cognitive problems, serious illness, poor vision or hearing, and past delirium.

Common triggers:

• infections, including urinary and chest infections
• surgery and anesthesia, especially hip fracture and heart surgery
• medications, particularly sedatives, opioids, and anticholinergic drugs
• alcohol or benzodiazepine withdrawal
• dehydration, low sodium, low blood sugar, or low oxygen
• untreated pain, constipation, or urinary retention
• sleep deprivation and the disorientation of an ICU or hospital ward

Treatment

Treatment starts with the cause: treat the infection, stop or reduce the drug that's doing it, correct the fluids and salts, manage the pain.

Alongside that, supportive care makes a real difference. That means a calm, well-lit room during the day and dark at night, glasses and hearing aids in place, a clock and calendar, familiar faces, regular fluids and food, getting out of bed early, and protecting sleep. The NICE delirium guideline recommends this multicomponent approach for both prevention and treatment.

Medication has a narrow role. Guidelines reserve short-term, low-dose antipsychotics for people who are very distressed or at risk of harming themselves or others, when other steps haven't worked. A Cochrane review found antipsychotics didn't reduce delirium severity or resolve symptoms compared with other approaches, though the evidence was rated low to very low quality. Sedating people who are quietly confused doesn't help them. Benzodiazepines can make delirium worse, with one important exception: they're the standard treatment for alcohol withdrawal delirium.