European studies on the prevalence of dementia in the elderly: time for a step towards a methodological consensus.

ABSTRACT

OBJECTIVE: The aim of this study was to discuss methodological limitations in studies on the prevalence of dementia across European countries with particular attention to post-EURODEM studies. METHODS: Two people independently focused on an iterative literature search for studies published in the years 2000-2012 using the following keywords 'dementia', 'Alzheimer', 'incidence', 'prevalence' that were cross-linked with names of European countries. After that, the results obtained were compared and publications in English were included in a subsequent analysis. RESULTS: We included 26 studies published in the years 2000-2012. The majority of epidemiological studies come from Spain and Italy. The past decade has not provided prevalence rates from a considerable number of countries. There is also a lack of nationwide surveys on the prevalence of dementia. Predominantly, epidemiological studies on the prevalence of dementia follow a two-stage approach that consists of a screening phase and a subsequent confirmation of dementia. However, several differences, particularly with regard to the neuropsychological instruments used, still exist and contribute to inconsistent prevalence rates. CONCLUSIONS: Although the EURODEM study was a milestone in the epidemiology of dementia in Europe and provided several future directions for research, methodological limitations are apparent in a number of European studies on the prevalence of dementia and require particular attention. In particular, a variety of diagnostic instruments requires unification for future studies. On the other hand, given the lack of epidemiological studies from a number of countries and the increasing prevalence of dementia, the need for population-based surveys should be emphasized.