Delirium is an acute neuropsychiatric disorder of attention and cognition, frequently precipitated by acute illness, trauma and/or surgery.1–4 Studies conducted more than 60 years ago showed that experimental hypoxia and hypoglycaemia lead to delirium-like clinical and EEG findings.5 The findings of elevated concentrations of CSF lactate and decreased neuron-specific enolase during delirium6 have suggested that cerebral metabolic insufficiency may potentially underlie delirium. This evidence concerns the gene ENO2 and delirium.