The epidemiology of the dementias: an update.
The epidemiology of dementia is one of the priority fields in aging research. This review aims to highlight the most relevant findings over last years concerning occurrence, risk factors, and prevention of dementia and its major subtypes. It is estimated that currently around 24 million people have dementia in the world, with the number being projected to double every 20 years, and that 60% of dementia patients live in developing countries, with the proportion being raised to more than 70% by 2040. Current evidence suggests that vascular factors, such as midlife hypertension, diabetes, and cerebrovascular disease, contribute significantly to the development of dementia and Alzheimer's disease, and that active engagement in mental, physical, and social activities may postpone the onset of dementia by providing cognitive reserve. Dementia represents a major public health challenge as a consequence of rapid increase in the aging population worldwide, especially in developing countries. This challenge can be partly confronted by successful development of preventive strategies. Evidence has emerged that proper control of vascular disorders and maintenance of active lifestyles may prevent or delay the onset and progression of dementia and Alzheimer's disease. Intervention trials are warranted to determine, to what extent, such programs are effective against dementia.