Delirium = an acute confusional state with fluctuating course, impaired attention, and altered awareness.  
It is very common in older adults (affects ~20–30% of hospitalised elderly) and is associated with ↑ morbidity, mortality, and length of stay.  
It is a medical emergency because it often signals an underlying illness.
⚡ Clinical Features (Core)
- ⏱️ Acute onset: Hours to days (contrast with dementia).
- 🔄 Fluctuating course: Worse at night (“sundowning”).
- ⚖️ Inattention: Can’t focus, distractible (months of the year backwards test).
- 🧭 Disorientation: Time/place/person.
- 🔊 Altered consciousness: Hyperactive (agitated, hallucinating), hypoactive (quiet, withdrawn), or mixed.
📊 Subtypes
- 🔥 Hyperactive: Agitated, hallucinations, aggressive (easier to recognise).
- 😴 Hypoactive: Quiet, withdrawn, sleepy (often missed — most common in frail elderly).
- 🔄 Mixed: Features fluctuate between hyper and hypo.
📋 Diagnosis
- 🧪 Clinical diagnosis: Based on acute onset + inattention + fluctuating course + altered awareness.
- ⚡ Bedside tests: Months backwards, digit span, attention tasks.
- 📊 Screening tools: 
- 4AT (rapid, validated, NICE recommended).
- CAM (Confusion Assessment Method).
 
 Key distinction: Delirium = acute, fluctuating, impaired attention.  
 Dementia = chronic, progressive, attention intact until late.
🧾 The 4AT – Rapid Delirium Screening Tool
The 4AT is a validated bedside tool to screen for delirium and cognitive impairment.  
Takes <2 minutes, no special training required.  
Score ≥4 = possible delirium, 1–3 = possible cognitive impairment, 0 = unlikely.
 
   | Item | Description | Scoring | 
   | 1️⃣ Alertness | Observe: normal, sleepy, agitated?  
     If clearly abnormal (drowsy/agitated), score higher. | 
0 = Normal (fully alert)4 = Clearly abnormal (drowsy, stupor, agitation) | 
   | 2️⃣ AMT4 (Abbreviated Mental Test – 4 items) | Ask: age, date of birth, place (hospital, building), current year. | 
0 = All correct1 = 1 error2 = ≥2 errors or untestable | 
   | 3️⃣ Attention | Ask patient to say months of the year backwards (start at December). | 
0 = ≥7 months correctly1 = 5–6 months2 = <5 months or refuses/unable | 
   | 4️⃣ Acute change or fluctuating course | From collateral history / observation.  
     Has there been an acute change (days) or fluctuation in mental state? |  | 
📊 Scoring Interpretation
- ≥4 = Possible delirium (+/- cognitive impairment).
- 1–3 = Possible cognitive impairment (dementia, mild cognitive impairment, or delirium).
- 0 = Delirium or cognitive impairment unlikely (but clinical judgement required).
 Note: 4AT is a screening tool, not a diagnostic test.  
 If score is positive, further assessment & collateral history essential.
📝 OSCE / Exam Pearls
- Demonstrate “months backwards” test confidently.
- Always mention collateral history (“Has there been a sudden change?”).
- Differentiate delirium vs dementia: attention is impaired in delirium.
- In practice: combine 4AT with full medical workup (“PINCH ME” causes).
🔎 Common Causes (“PINCH ME” mnemonic)
- 🧪 Pain
- 💉 Infection (UTI, pneumonia, sepsis)
- ⚡ Nutrition (dehydration, malnutrition, thiamine deficiency)
- 💊 Constipation/urinary retention
- 🏥 Hypoxia (PE, pneumonia, MI)
- 🧠 Medications (opioids, benzos, anticholinergics, steroids, digoxin)
- 🩸 Electrolyte/metabolic (Na, Ca, glucose, renal/hepatic failure)
🧑⚕️ Investigations
- 📋 Full history + collateral from carers/family (baseline cognition important).
- 🩺 Examination: systemic + neurological.
- 🧪 Bloods: FBC, U&E, Ca, CRP, glucose, LFTs, TFTs, B12/folate.
- 🦠 Urinalysis & culture, CXR, ECG.
- 🧠 CT head if head injury, neuro deficit, or cause unclear.
- 🚽 Bladder scan (urinary retention) & PR (faecal impaction).
🛡️ Prevention (NICE guidelines)
- 💧 Maintain hydration & nutrition.
- 🛏️ Promote sleep hygiene & avoid unnecessary bed moves.
- 👓 Sensory aids: ensure glasses/hearing aids in use.
- 🚶 Early mobilisation & physio.
- 🗓️ Orientation: clocks, calendars, regular reorientation, family involvement.
- 💊 Avoid high-risk drugs (anticholinergics, benzos, opioids if possible).
🛠️ Management Principles
- 🔍 Identify and treat underlying cause (infection, drugs, retention, constipation, metabolic disturbance).
- 🛌 Supportive environment: Quiet room, good lighting, minimise noise, consistent nursing staff.
- 💬 Reassurance: Frequent orientation, involve family/carers.
- 🚶 Encourage early mobilisation, physiotherapy, avoid restraints.
- 👓 Ensure sensory aids used consistently.
- 💊 Medications: 
- Antipsychotics only if severe distress or risk to self/others.
- Haloperidol (0.5–1 mg PO/IM) first-line unless Parkinson’s/LBD.
- Quetiapine preferred in Parkinson’s/Lewy body dementia.
- Benzodiazepines reserved for alcohol withdrawal delirium.
 
🚨 Prognosis & Complications
- 📈 Delirium is associated with 2–3x ↑ mortality.
- 🧠 Can precipitate long-term cognitive decline or worsen dementia.
- 🏥 ↑ hospital stay, ↑ risk of institutionalisation.
📝 OSCE / Exam Pearls
- Always ask for collateral history (baseline vs acute change).
- Use 4AT tool in stations (rapid and examiners like it).
- Mention “PINCH ME” mnemonic for causes.
- State non-drug measures first; reserve drugs for severe distress/risk.
- Always distinguish delirium vs dementia: attention is impaired in delirium.
🎯 Key Takeaway
Delirium in the elderly = acute, fluctuating, often reversible.  
It is a red flag for underlying illness.  
Always look for triggers with “PINCH ME”, provide supportive care, and use antipsychotics sparingly.  
Early recognition prevents complications and saves lives. 🌟