Harmonized prevalence estimates of dementia in Europe vary strongly with childhood education

Abstract

Up-to-date, strictly cross-nationally comparable and nationally representative data on cognitive health are essential for our understanding of the dementia-related challenges in healthcare, to detect shortcomings in healthcare systems and to design effective prevention strategies. Such data have been missing in Europe. We use the most recent 2022 wave of the strictly harmonized Survey of Health, Ageing and Retirement in Europe (SHARE, 47,773 individuals age 65 and older) to obtain prevalence estimates of mild cognitive impairment and dementia for 27 European countries and Israel in 2022. The novelty of the paper is to validate these estimates using the Harmonized Cognitive Assessment Protocol (HCAP) as a validation tool. These new data exhibit much higher prevalence rates of dementia in the Mediterranean and Southeastern European countries and a much larger variation of cognitive impairment across Europe and Israel than previously known. Dementia prevalence ranges from 4.5% in Switzerland to 22.7% in Spain, MCI prevalence from 17.2% in Sweden to 31.1% in Portugal. Most of this variation can be explained by differences in education when respondents were young. Prevalence rates vary plausibly with other risk factors such as age and comorbidities associated with dementia.

Keywords: Cognition; Cross-national comparisons; Dementia; Education; Europe; Prevalence.

Fig. 1

Association between the probability of being demented and frequent comorbidities of dementia. The blue dots show the percentage by which the presence of a comorbidity decreases/increases the probability of being demented. The error bands denote 95% confidence intervals. For example, having had a diagnose of a stroke increases the probability of being demented by 7.2% which is statistically significant, while high blood pressure does not have a statistically significant association with dementia conditional on the other co-morbidities. All associations are conditional on age, sex and education.

Fig. 2

Prevalence of dementia for 27 European countries and Israel. Actual and counterfactual if education had been equal across all countries. The red bars show the actual estimated share of demented individuals in each country. The grey bars show the counterfactual share of demented individuals if education in each country had been equal to the average of the 28 countries.