Delirium !
Sudden confusion with poor attention that comes and goes, caused by an illness, a drug or surgery. Common in older and ICU patients, and often preventable.
Updated 2026-11-01
Structures involved
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In the clinical exam
- General inspection: appearance, posture, gait and consciousness
- Comprehensive geriatric assessment: function, cognition, falls
- The neurological examination: order and screening exam
- Mental status: orientation, attention and screening tests
Why it happens
What it is
An acute, fluctuating disturbance of attention and awareness with disorganised thinking or other cognitive changes, caused by a medical condition, a substance or its withdrawal. It develops over hours to days, is a medical emergency, and is especially common in older adults, after surgery and in intensive care.
Who gets it
Affects a large share of hospitalised older adults, many patients after hip fracture surgery and most mechanically ventilated ICU patients. It is under-recognised, mainly because the quiet hypoactive form is mistaken for tiredness or depression. With population ageing in Colombia and Latin America, it is a growing problem in emergency, medical and surgical wards.
Causes
- Infections: urinary tract infection, pneumonia, sepsis
- Medicines: anticholinergics, benzodiazepines, opioids, sedating antihistamines, corticosteroids, polypharmacy
- Withdrawal from alcohol or sedatives
- Metabolic disorders: hypoglycaemia, hyponatraemia, hypercalcaemia, dehydration, kidney or liver failure
- Hypoxia, heart failure, stroke, head injury
- Surgery and anaesthesia, pain, urinary retention, constipation, sleep deprivation
Risk factors
- Age 65 years or older
- Dementia or previous cognitive impairment
- Severe illness, hip fracture or major surgery
- Visual or hearing impairment
- Frailty, malnutrition and dehydration
- ICU stay with mechanical ventilation and deep sedation; physical restraints and urinary catheters
Pathophysiology
A widespread, usually reversible failure of brain networks triggered by systemic illness. Inflammation, reduced oxygen and glucose delivery and drug effects disturb neurotransmission, with relative acetylcholine deficiency and dopamine excess. Networks for attention and arousal (thalamus, prefrontal and parietal cortex, brainstem reticular system) are the most affected, which explains inattention and a fluctuating level of consciousness.
Classification
- Hyperactive: agitation, restlessness, hallucinations, pulling at lines
- Hypoactive: drowsiness, slowness, withdrawal; the most common form in older adults and the most often missed
- Mixed: alternates between the two
Symptoms and signs
- Acute onset over hours to days, fluctuating during the day and often worse at night (sundowning)
- Inattention: easily distracted, unable to follow a conversation
- Disorganised thinking and rambling speech
- Altered level of consciousness, from drowsy to hyperalert
- Disorientation and memory problems
- Visual hallucinations, illusions and paranoid ideas
- Disturbed sleep-wake cycle
Diagnosis
- Clinical
- Clinical diagnosis based on acute onset and fluctuation, inattention, and disorganised thinking or altered consciousness. Validated tools include the Confusion Assessment Method (CAM), the CAM-ICU with the RASS sedation scale in intensive care, and the 4AT. A collateral history establishes baseline cognition; a medication review and examination look for the cause.
- Tests
- Glucose, electrolytes including sodium and calcium, kidney and liver function, complete blood count, urinalysis and cultures guided by symptoms, oxygen saturation or blood gases, ECG, and drug levels or toxicology when relevant. Lumbar puncture if meningitis or encephalitis is suspected; EEG typically shows diffuse slowing and helps exclude non-convulsive seizures.
- Imaging
- Chest X-ray when infection or heart failure is suspected. Head CT when there are focal signs, head trauma, anticoagulation, or no other cause is found.
Differential diagnosis
- Dementia (gradual onset, attention preserved until late; but dementia and delirium often coexist)
- Depression (especially versus hypoactive delirium)
- Primary psychotic disorder (attention and orientation usually preserved)
- Non-convulsive status epilepticus
- Aphasia from stroke
Goal of treatment
Find and treat every underlying cause, keep the patient safe and comfortable, avoid drugs that worsen confusion, and preserve function, while preventing delirium in people at risk.
Treatment
- Acute
- Treat the causes: infection, dehydration, hypoxia, electrolyte and glucose disorders, pain, urinary retention and constipation; stop or reduce deliriogenic drugs.
- Conservative
- Multicomponent non-drug care is the core of prevention and treatment: frequent reorientation (clock, calendar, family), glasses and hearing aids, sleep hygiene with day-night lighting, early mobilisation, hydration and nutrition, and avoiding restraints and unnecessary catheters.
- Medical
- Antipsychotics are used only short-term for severe agitation or distressing psychosis that puts the patient at risk; they do not prevent or shorten delirium. Benzodiazepines are avoided except for alcohol or sedative withdrawal.
- Follow-up
- Monitoring: screening with CAM, CAM-ICU or 4AT every shift in high-risk patients; in the ICU, light sedation, daily awakening and breathing trials, and the ABCDEF bundle.
- Rehabilitation
- Early physiotherapy and occupational therapy, and follow-up of cognition and function after discharge.
Complications
- Falls and fractures
- Pressure injuries, aspiration pneumonia and malnutrition
- Longer hospital stay and institutionalisation
- Long-term cognitive decline and accelerated dementia
- Higher mortality
Prognosis
Often reversible when the cause is treated, but recovery can take weeks and some patients never return to their previous level. Delirium is an independent marker of higher mortality, functional loss and later dementia, especially in older and ICU patients.
Prevention
- Multicomponent prevention programmes for older inpatients (such as the Hospital Elder Life Program) clearly reduce new cases
- Medication review to avoid anticholinergics, benzodiazepines and polypharmacy
- Good pain control, early mobilisation and family presence after surgery
- Light sedation and early mobilisation in the ICU
Test yourself
Think of the answer, then tap the question to see it.
What is the core cognitive feature that distinguishes delirium from dementia?
Acute onset with fluctuating inattention and altered awareness; dementia is gradual with attention preserved until late.
Which form of delirium is most common in older adults and most often missed?
Hypoactive delirium.
Which tool is used to screen for delirium in intubated ICU patients?
The CAM-ICU, together with the RASS sedation scale.
What intervention has the best evidence to prevent delirium in hospitalised older adults?
Multicomponent non-pharmacological measures: reorientation, sensory aids, sleep, mobilisation, hydration and medication review.
In which situation are benzodiazepines the treatment of choice for delirium?
Delirium caused by alcohol or sedative-hypnotic withdrawal.
Related conditions
- Alcohol withdrawal and delirium tremens
- Sepsis and septic shock
- Urinary tract infection (acute cystitis)
- Community-acquired pneumonia
- Alzheimer disease
- Parkinson disease
- Subdural haematoma
- Femoral Neck Fracture
- Ischaemic stroke
- Bacterial meningitis
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Delirium (MedlinePlus (U.S. National Library of Medicine), 2025).
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