Delirium versus dementia
| Feature | Delirium | Dementia |
|---|---|---|
| Onset | Abrupt/sub-acute | Insidious |
| Course | Fluctuating | Slow progression |
| Duration | Hours–weeks | Months–years |
| Alertness | Abnormally high or low | Typically normal |
| Sleep-wake | Disrupted | Typically normal |
| Attention | Impaired | Relatively normal |
| Orientation | Impaired | Intact in early dementia |
| Working memory | Impaired | Intact in early dementia |
| Episodic memory | Impaired | Impaired |
| Thought | Disorganised, delusions | Impoverished |
| Speech | Slow/rapid, incoherent | Word finding difficulty |
| Perception | Illusions/hallucinations common | Usually intact in early dementia |
| Behaviour | Withdrawn/agitated | Varies: often intact early |