Alzheimer's Disease
Prevalence
Prevalence of dementia increases with age. Because of the ageing of the world population, there will be relatively more people in the age groups with higher risk for dementia in the future.
Prevalence refers to the number of people with a certain disease in the population at a given point in time. There are a large number of surveys that analyse the prevalence of dementia. These tend to give slightly different results depending on the methods used in the study.
The diagram below depicts an estimate of the world-wide occurrence of dementia based on the best available data on age-class-specific dementia prevalence (Fratiglioni L., Rocca WA: Epidemiology of dementia; in Boller F, Cappa SF (eds.): Handbook of Neuropsychology, ed 2. Amsterdam, Elsevier, 2001, pp 193 - 215) and the world-wide demographic statistics from the United Nations, the so-called World Population Prospects (1998).
As an example between 1990 and 2010 the number of dementia cases in the more developed countries is projected to increase from 7,4 million to 10,2 million (a 37% increase), the elderly population (aged 65+) will increase from 143 million to 185 million (a 30% increase), while the total population in these countries is projected to increase only from 1.143 million to 1.213 million (a 6% increase).