The evidence that prevention of Alzheimer's disease is an achievable goal is growing. This meta-analysis summarises the current knowledge and underlines possible gaps to be filled in the near future

The prevalence of dementia in the world is around 50 million and is increasing rapidly. Most projections estimate that by 2050 there will be more than 150 million people with dementia, with a predicted cost of two trillion dollars by 2030.1

The most common dementia is Alzheimer's disease (AD), comprising 60–80% of the total. To date no disease-modifying treatments are available for AD or for any other form of dementia. Therefore, strategies to prevent AD to cope with the huge public health problem are urgently needed. The literature investigating risk factors for AD and other dementias is an essential base on which to build preventive strategies.

The strongest indication that prevention of dementia and AD may be possible is the recently declining incidence shown in many studies, both in Europe and the USA.2 More recently, an analogous trend has been shown in Asia, with a 40% decline in the incidence of dementia and AD over 12 years in South Korea.3

The most likely factors responsible for this trend have been improvement of vascular health with the introduction of effective treatments, especially for hypertension, and in the past decades, improvement of education, generally measured …