Delirium is an acute clinical emergency that requires prompt clinical intervention. A predisposing factor for delirium is dementia, and delirium may highlight the vulnerability of a patient to developing dementia. However, delirium also occurs during an acute illness in patients diagnosed with dementia; this is classified as delirium superimposed on dementia. This complex interplay of both dementia syndromes and the condition of delirium has been extensively studied. However, delirium continues to be under-recognised in the acute setting, which impacts negatively on patient outcomes. To read the full article, log in using your NHS OpenAthens details.