This article is the first in a series of five focusing on the needs of patients with dementia. The number of people with dementia accessing acute care is rising. The need for acute hospital care to adapt to demographic changes and to reflect these in the acute hospital structure is emphasised. The most common forms of dementia, including Alzheimer's disease, vascular dementia and Lewy body dementia, are discussed. The psychosocial aspects of this condition also need to be considered to promote nursing care that is sensitive to patients' needs.