Global prevalence of dementia

Abstract

Dementia is one of the most disabling conditions worldwide. Estimates based on an expert consensus show that more than 24 million people have dementia today and that numbers of people affected will double every 20 years to more than 80 million by 2040. Up to two thirds live in low and middle income countries. With the ageing of the population in these countries this proportion is also rising. Review of population-based studies on prevalence of dementia conducted in the 21 WHO world regions. Evidence on prevalence of dementia is missing for some regions. Prevalence of dementia is not uniform between countries, being somehow lower in some developing countries such as India and Nigeria. Differences on prevalence between countries might be due to differences in diagnosing dementia in these different settings. Differences in the level of exposure to environmental risk factors and patterns of mortality in early life might also be implicated. As patterns of morbidity and mortality converge with those of the richer countries, prevalence of dementia and other chronic conditions will do likewise, leading to an increased burden in poorer countries.