Association between Year of Birth and Cognitive Functions in Russia and the Czech Republic: Cross-Sectional Results of the HAPIEE Study

Objectives: To assess differences in cognitive functions by year of birth in Russia and the Czech Republic. Methods: A cross-sectional study in the general population of Novosibirsk (Russia) and 6 cities of the Czech Republic recruited random samples of men and women (3,874 Russians, 3,626 Czechs) aged 45-69 years in 2002 (i.e. born in 1933-1957). Word recall, verbal fluency (number of animals named in 1 min) and letter search were assessed in a clinic. Results: Except letter search in men, we found similar levels of cognitive functioning in Russians and Czechs in the youngest subjects and a steeper association of functioning with year of birth in Russia than in the Czech Republic. For example, the difference in the mean word recall, associated with 10 years difference in year of birth, was 0.9 (SE 0.06) words in Russian men, compared to 0.4 (0.06) words in Czech men; in women, these figures were 0.8 (0.05) and 0.3 (0.05), respectively. For all outcomes, except letter search in men, the interactions between year of birth and country were statistically highly significant, and the differences in the year of birth effects between countries were largely unexplained by socioeconomic indicators and risk factors. Conclusion: The slope of association between lower cognitive functioning and earlier year of birth is much steeper in Russia than in the Czech Republic. Given that poor cognitive functioning is a risk factor for dementia, long-term follow-up of this cohort and other studies into population rates of cognitive impairment in Russia should be a priority. Copyright (c) 2009 S. Karger AG, Basel