Delirium is acute and fluctuating with inattention; dementia is chronic and progressive
Mnemonic
PINCH ME, for the reversible causes of delirium:
- P - Pain
- I - Infection
- N - Nutrition, including thiamine
- C - Constipation
- H - Hydration and hypoxia
- M - Medication, especially anticholinergics, opioids, benzodiazepines, and withdrawal
- E - Environment and electrolytes
“Inattention is the cardinal feature”: ask for the months of the year backwards. It is what separates delirium from dementia, in which attention is preserved until late.
The 4AT formalises it: alertness, AMT4, months backwards, and acute change or fluctuation. A score of 4 or more suggests delirium.
Hypoactive delirium is the commonest form and the most missed, and it carries the worse prognosis, because the withdrawn, drowsy patient does not draw attention to themselves.
Expansion
| Feature | Delirium | Dementia |
|---|---|---|
| Onset | Acute, hours to days | Insidious, months to years |
| Course | Fluctuating, worse at night | Progressive, stable through the day |
| Attention | Impaired, the cardinal feature | Preserved until late |
| Consciousness | Altered | Clear until late |
| Hallucinations | Common, often visual | Less common early |
| Reversibility | Usually reversible | Not reversible |
Causes of delirium (PINCH ME): Pain, INfection, Constipation, deHydration, Medication, Electrolytes. Add urinary retention, alcohol withdrawal, hypoxia, hypoglycaemia and intracranial events.
Hypoactive delirium is commoner than the hyperactive form and is far more often missed, presenting as quiet withdrawal rather than agitation. It carries a worse prognosis.
Assessment tools: 4AT for rapid screening, and the confusion assessment method. Cognitive testing with AMT-10, MoCA or ACE-III is for dementia rather than acute delirium.
Management is of the cause, with reorientation, familiar objects, hearing aids and glasses, sleep hygiene, mobilisation and avoidance of catheters and restraints. Sedation is a last resort and worsens outcome.
Delirium is a marker of vulnerability, associated with increased mortality, length of stay and subsequent dementia.