The importance of knowing the prevalence of dementia in Europe

At a regional, national and international level, strategic planning of health and social policy is dependent on accurate estimation of the size of the challenge, and with this comes an ability to estimate the future cost of the care, support and treatment needed. At an individual level the ability of patient associations to be able to offer evidence-based knowledge to patients and caregivers is a minimal expectation. Knowledge about the numbers of people affected by dementia is therefore essential.

The following tables provide details of the prevalence of dementia within the EU-28 countries, as well as in Jersey, Iceland, Norway, Switzerland and Turkey. We have separated both sets of countries so as to have a figure for the European Union, and one for additional countries in which Alzheimer Europe has a member association.

What we mean by prevalence

When we use the term “prevalence”, we are referring to the estimated proportion of individuals in a given population that have a particular condition, in this case dementia,  at a specific time. This includes people who have recently developed dementia, as well as those who have already had the condition for some time (i.e. incident and prevalent cases). A prevalence rate is the total number of cases of a disease in a known population divided by the total population (New York State Department of Health, 1999). This differs from an incidence rate which measures the number of new cases of a condition divided by the number of people at risk for the condition, starting from a group of people who do not yet have it. In other words, incidence rates represent the rate at which new cases develop in the population, whereas prevalence rates provide a snapshot of the health status of a particular population at a given time (Prince, 2008). The figures we present here concern the latter. 

How we calculated the prevalence figures for this report

For our calculations, we used projected population statistics from the United Nations for 2012 and two sets of prevalence rates. The resulting figures which you can see in the tables are the result of multiplying the population in given age groups (i.e. 30 to 59, followed by 5-year age groups, ending with 95+) with one of two sets of prevalence rates:

1. Prevalence rates from the EURODEM study were used to calculate the prevalence of dementia in the 30 to 59 age group. EURODEM (1991) was an EU-funded study, based in the Erasmus Medical Centre, Rotterdam. This was a collaborative study involving the analysis of 12 population-based epidemiological studies from 8 countries in relation to the prevalence of dementia. The results were published in an article by Hofman et al. (1991) and the work was updated in 2000. The studies are highly relevant today even though they were based on cohorts commenced in the 1980s, and do not include data from Eastern Europe (Alzheimer Europe, 2013).
2. Prevalence rates from the EuroCoDe study were used to calculate the prevalence of dementia in the 60 to 95+ age groups. EuroCoDe (2008) was also an EU-funded project, co-ordinated by Alzheimer Europe, involving 6 work packages. Emma Reynish was the leader of the work package, whose aim was to develop prevalence rates for dementia. A total of 194 articles were identified from the literature search. 31 studies were identified as possible for inclusion in collaborative analysis and the researchers of those studies were invited to submit data. Raw data was obtained from 17 studies and used in the collaborative analysis of dementia prevalence rates in Europe. Reynish and her colleagues also analysed epidemiological data for prevalence rates for early onset dementia but found that this was sparse and involved studies with low numbers and wide variation in rates, perhaps due to differing study designs. They did not therefore develop new prevalence rates for younger people with dementia and this is why we are using a combination of two different sets of rates.

For full details of the prevalence rates used, please see Alzheimer Europe (2013) and Hofman et al. (1991).  

Table 1. The Prevalence of Dementia in Europe (EU-28)

Table 2.The Prevalence of Dementia in Europe

Jersey, Iceland, Norway, Switzerland and Turkey

                                                Table 3. The Grand Total