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Prevalence of dementia

European Collaboration on Dementia


The project will gather existing epidemiological studies and analyse the respective merits and shortcomings of the individual studies. Based on the report on these studies, consensual European prevalence rates will be developed that will be acceptable to all partners and used as a “golden standard” within the respective organisations.

Workpackage Members

E Reynish

Toulouse/ Edinburgh

Toulouse University Hospital

L Fratiglioni


Karolinska Institutet

M Prince


Kings College

Horst Bickel


Technische Universität München

Andrzej Kiejna


Medical University of Wroc?aw

Jean Georges


Alzheimer Europe


Dementia generally has an insidious onset, progresses slowly over years and death is usually due to intercurrent illness, rather than the disease itself. The resulting impact on quality of life, the social / caregiver burden and healthcare systems is significant. This global burden will rise with increasing longevity. The World Health Organisation (WHO) stated in 1997 “Increased longevity without quality of life is an empty prize, health expectancy is more important than life expectancy”

Currently one of the most significantly changing global demographic factors is the increase of life expectancy. In 1950, life expectancy at birth for a European male was 63.4 years; today it is 70.5 years (United Nations, World Population prospects). In addition European birth rates soared after the Second World War. In 2006 the first of this generation turned 60. This change in birth rate and increasing life expectancy has brought about a rapid demographic change in Europe with an increasing number of people living over the age of 60. For example in Germany the dependency ration (the proportion of people over 65 to those aged 20-64) has hovered around 25% for the last 30 years. It is predicted to reach 50% over the next 30 years. The primary risk factor for the development of dementia is age. The demographic shifts in the EU population significantly increase in the number of people at risk of dementia.

Knowledge about the numbers of individuals affected by dementia is essential. For the research community hypothesis generation is often driven by epidemiological data. At a regional, national and international level strategic planning of health and social policy is dependant on accurate estimation of the size of the problem, and with this comes an ability to estimate the future cost of the disease burden. 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.

In 1991 EURODEM (EU funded) based in Erasmus Medical Centre, Rotterdam, published a collaborative study of 12 population based epidemiological studies from 8 countries looking at the prevalence of dementia in Europe. The work was updated in 2000. The articles are highly relevant today but are based on cohorts commenced in the 1980’s, and does not include data from Eastern Europe. In addition to the important collaborative prevalence data resulting from this work, the project had huge methodological significance in that the differences in epidemiological methods used and resulting study quality across Europe was discussed and minimum standards for future work were proposed. The quality of population based epidemiological studies performed since this time have enormously benefitted from EURODEM discussions.

Since the EURODEM publications world prevalence rates for dementia have been estimated using entirely different methodology. DELPHI consensus methods were used to review global prevalence and estimates for prevalence for each continent were published in 2005. “Delphi consensus is a method for making estimates where an evidence base exists but data are incomplete, scanty or otherwise imperfect. The essence of the method is deriving quantitative estimates through the qualitative assessment of research evidence. It is an interactive process of consensus. Experts first make estimates independently, which are then aggregated and fed back anonymously so that they may review them in the light of group-wide choices.” This project considered prevalence rates for all continents. That for Europe was based on reviewing evidence from just 4 European Studies of prevalence and did not provide age and sex specific rates.

This project, by means of an extensive literature search using Cochrane review methodologies, has compiled a database of all European epidemiological studies in this field up to the present date.

Systematic reviews of 1) prevalence of dementia, 2) prevalence of early onset dementia and 3) prevalence of Dementia in Eastern Europe have been performed.

Data from high quality studies performed in the last 20 years looking at dementia prevalence have been pooled in a collaborative analysis. Age and sex specific prevalence rates have been calculated using this prevalence data. An outline of the components of the project are presented in Fig. 1

Methods and results of each of these component parts will be described separately in the report.



Last Updated: Thursday 13 August 2009