[Epidemiology of Alzheimer's disease and other dementias].

INTRODUCTION: Dementia is a clinical syndrome resulting from a number of causations and which is usually accompanied by progressive and diffuse brain dysfunction. The different subtypes are characterised by a clinical picture with common symptoms that differ in terms of their aetiology, age, clinical presentation, clinical course and associated disorders.

AIM: To present an update on the information available about the descriptive epidemiology of dementia and its main subtypes.

DEVELOPMENT: The main data on prevalence, incidence and mortality were extracted from a literature review. Alzheimer's disease is the most frequent subtype and accounts for 60-80% of all the cases, followed by vascular dementia and other neurodegenerative dementias, such as dementia due to Lewy bodies, the dementia-Parkinson complex and frontotemporal dementia. Other subtypes of dementias present frequencies below 1%, and the epidemiological indicators available are not very robust.

CONCLUSIONS: The prevalence and incidence of dementia increase exponentially from the age of 65 onwards. As a consequence of the progressive ageing of the population and the increase in life expectancy, the number of cases of dementia will rise in the coming decades. Recent studies point to a slight drop in the accumulated risk of dementia adjusted by age groups and sex over the last few decades in some countries. It is possible that by means of primary prevention strategies implemented upon the known risk factors for dementia the burden of dementia on public health will diminish in the future.