Why Delirium Is Examined
Delirium is the most common acute neuropsychiatric syndrome in hospital settings, affecting up to 30% of elderly inpatients. It is associated with increased mortality, longer hospital stays, and accelerated cognitive decline. OSCEs test it through: structured assessment stations, communication stations (explaining delirium to a relative), and clinical reasoning scenarios (acutely confused elderly patient — what do you do?).
💡 Tip
The most important concept: Delirium is never a diagnosis in itself — it is always a symptom of an underlying medical cause. Your job is to identify and treat the cause, not manage the confusion in isolation.
Diagnostic Criteria — DSM-5
Delirium requires all four of the following:
- 1Disturbance of attention and awareness
- 2Acute onset and fluctuating course (hours to days)
- 3Cognitive disturbance (memory, orientation, language, visuospatial, perception)
- 4Not explained by pre-existing neurocognitive disorder, coma, or other condition
Clinical Subtypes
| Subtype | Features | Risk |
|---|---|---|
| Hyperactive | Agitation, restlessness, hallucinations, combativeness | Easily recognised — risk of falls, line removal |
| Hypoactive | Quiet, withdrawn, reduced responsiveness | Most common and most missed — often labelled "just tired" |
| Mixed | Alternates between hyperactive and hypoactive | Common in older adults |
⚠️ Red Flag
Hypoactive delirium carries the worst prognosis and is most frequently missed. An elderly patient who is quiet, staring, not eating, and "not themselves" may have delirium — not depression or exhaustion. Always screen.
The 4AT Tool (Validated UK Screening Tool)
The 4AT is recommended by NICE, SIGN, and the British Geriatrics Society for delirium screening. It takes under 2 minutes.
Item 1: Alertness
Observe the patient during the assessment.
- Normal (fully alert) = 0
- Mild sleepiness (under 10 seconds), easily roused = 0
- Clearly abnormal (agitated, drowsy, not maintaining alertness) = 4
Item 2: AMT4 (Abbreviated Mental Test — 4 questions)
Ask: (1) Age; (2) Date of birth; (3) Place (name of hospital); (4) Current year.
- 4 correct = 0
- 2-3 correct = 1
- 0-1 correct = 2
Item 3: Attention
Ask patient to list the months of the year backwards starting from December.
- 7 or more months correctly = 0
- Starts but fewer than 7 months, or refuses = 1
- Cannot attempt = 2
Item 4: Acute Change or Fluctuating Course
Is there evidence of significant change in mental status in the past 2 weeks AND still present in the last 24 hours?
- No = 0
- Yes = 4
Scoring
| Total | Interpretation |
|---|---|
| 0 | Delirium unlikely (does not exclude subsyndromal delirium) |
| 1-3 | Possible cognitive impairment — investigate further |
| 4 or more | Delirium likely |
Causes of Delirium — PINCH ME
🧠 Mnemonic
PINCH ME — common precipitants:
- P ain
- I nfection (UTI, pneumonia, wound infection, sepsis)
- N utrition (dehydration, electrolyte disturbance, hypoglycaemia)
- C onstipation / urinary retention
- H ypoxia
- M edication (new, changed, or withdrawn — especially opioids, benzodiazepines, anticholinergics, steroids)
- E nvironment (unfamiliar, poor lighting, sensory impairment — glasses/hearing aids missing)
Predisposing factors (cannot be changed, increase vulnerability):
- Age over 65
- Pre-existing cognitive impairment / dementia
- Sensory impairment (vision, hearing)
- Dehydration
- Frailty and functional dependence
Investigations
| Investigation | Looking for |
|---|---|
| Urine dip plus MC&S | UTI |
| FBC, CRP, blood cultures | Infection, sepsis |
| U&E, eGFR | Electrolyte disturbance, renal failure |
| Blood glucose | Hypoglycaemia |
| TFTs | Hypo/hyperthyroidism |
| LFTs | Hepatic encephalopathy |
| Calcium | Hypercalcaemia |
| CXR | Pneumonia, heart failure |
| ECG | Arrhythmia, ischaemia |
| CT head | New focal neurology, post-fall, anticoagulated |
Management
Non-pharmacological (first-line for all patients):
- Reorient repeatedly — clock, calendar, familiar objects, photos
- Single side room if possible; minimise room changes
- Consistent nursing staff
- Restore normal sleep-wake cycle (avoid daytime sedatives, darken room at night)
- Ensure hearing aids and glasses are worn
- Encourage family presence and familiar voices
- Early mobilisation
- Treat underlying cause(s)
Pharmacological (for distressing or dangerous agitation only):
- Haloperidol 0.5-1 mg PO/IM (lowest effective dose, short duration)
- Lorazepam 0.5-1 mg if Parkinson's disease, LBD, or alcohol withdrawal (haloperidol contraindicated)
⚠️ Red Flag
Haloperidol is contraindicated in Lewy body dementia — it can cause severe irreversible parkinsonism and neuroleptic malignant syndrome. Always check dementia subtype before prescribing.
Delirium vs Dementia — Differentiation
| Feature | Delirium | Dementia |
|---|---|---|
| Onset | Acute (hours/days) | Gradual (months/years) |
| Course | Fluctuating (better and worse through day) | Progressive, relatively stable day-to-day |
| Attention | Markedly impaired | Intact until late |
| Consciousness | Altered | Normal until late |
| Reversibility | Usually reversible | Generally irreversible |
| Hallucinations | Common (visual) | Less common (except LBD) |
💎 Clinical Pearl
Dementia is the single biggest risk factor for delirium. Up to 65% of delirium episodes occur in patients with pre-existing dementia. Delirium can unmask previously undiagnosed dementia — always arrange cognitive follow-up after an episode.
Frequently Asked Questions
"What is the difference between delirium and dementia?"
The key distinguishing features are onset and attention. Delirium is acute (hours to days), fluctuates through the day, and causes marked impairment of attention. Dementia develops gradually over months to years, is relatively stable day-to-day, and attention is preserved until later stages. They can coexist — dementia is the strongest risk factor for delirium.
"Which medications commonly cause delirium?"
Anticholinergics (antihistamines, tricyclics, bladder antimuscarinics), opioids, benzodiazepines, corticosteroids, and certain antibiotics (fluoroquinolones, metronidazole). Benzodiazepine and alcohol withdrawal can also precipitate delirium. Always perform a medication review and discontinue or reduce precipitants where possible.
"Should all confused elderly patients have a CT head?"
Not routinely — only if there is new focal neurology, a fall with head injury, the patient is anticoagulated, or there is no obvious medical cause found on initial assessment. CT head is not part of the standard first-line delirium workup but should be considered if the presentation is atypical or not resolving as expected.
"How do I explain delirium to a relative?"
"Your relative is experiencing something called delirium — it means their brain is temporarily confused because of an illness or a change in their body. It can cause them to seem not like themselves, see things that aren't there, or be restless or very drowsy. The good news is that once we find and treat the cause, most people recover. The best things you can do are visit regularly, speak calmly, remind them where they are, and bring in familiar objects from home."
"How long does delirium last?"
Most episodes resolve within days to weeks once the underlying cause is treated. However, some patients — particularly older adults with pre-existing dementia — may take weeks to months to return to baseline, and some never fully recover. Persistent delirium beyond 4 weeks warrants further cognitive assessment and specialist review.
Related Posts
- Frailty Assessment OSCE — frailty as a predisposing factor for delirium
- Glasgow Coma Scale OSCE — quantifying conscious level in the acutely confused patient
- Medication Review OSCE — identifying deliriogenic medications as part of a structured review