Differentiation of delirium, dementia and delirium superimposed on dementia in the older person.

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. Nurses are the health professionals best placed to recognise a change in a patient's cognitive symptoms, but nurses caring for the older person have suggested the identification of and differentiation between delirium, dementia and delirium superimposed on dementia remains very confusing. A need for further education with supportive guidelines and protocols is required to empower nurses caring for an older person to verbalise changes in patients' cognitive status in a reliable, robust and systematic manner.