Epidemiology of the dementias: recent developments and new approaches.

Dementia is an important cause of disability in elderly people.Given the increase in the pro- portion of elderly people in most countries, the number of patients with dementia will rise and the care of these patients will have a growing impact on the healthcare system and society.The past decade has seen many successes in epidemiological studies of the aetiology of chronic disorders including car- diovascular disease, cancer, and osteoporosis.In this review, new developments in the epi- demiology of the dementias are discussed.Descriptive studies of the occurrence of dementia across different populations and time periods as well as studies of risk factors for dementia are reviewed.Dementia is a syn- drome that can be caused by many conditions.As Alzheimer's disease is the predominant cause of dementia, accounting for at least half of the cases in most populations, epidemiological research has focused on this disorder.