Background Cognitive reserve hypothesis suggest that highly educated individuals are less likely to manifest clinical symptoms of dementia compared to their less-educated counterparts. We aimed to examine the association between education, used as a marker of cognitive reserve, and change in Mini-Mental State Examination (MMSE) in preclinical stages of dementia in four European longitudinal studies of ageing.

Methods Participants, aged 80 and older, who developed dementia during the study period in each one of the four cohorts investigated: Newcastle 85+, UK (3 waves); Leiden 85+, Netherlands (6 waves); 3 Cities, France (5 waves) and OCTO-Twins, Sweden (5 waves) were included in these analyses. Each individuals’ cognitive scores were aligned according to the distance (years) to dementia diagnosis. Using a coordinated analysis approach, we employed multilevel models to investigate the role of education on change in MMSE while controlling for age at baseline (centred at 85 yrs in all studies), sex, and time to dementia diagnosis from study entry within each study. Education was classified in low versus higher levels ( > 10 years).

Results In two out of four cohorts (Newcastle 85+ and 3 Cities), higher education was associated with higher MMSE scores at the time of dementia diagnosis compared to those with lower education (with β = 4.44, SE = 1.45, p < 0.01 and β = 1.11, SE = 0.28, p < 0.001 respectively). Higher education had a moderating role on the rate of change in MMSE from the study entry to the time of dementia diagnosis in the British cohort with 1.25, SE = 0.26, p < 0.01 slower decline compared to those with lower education, but a reverse effect in the Dutch cohort, where higher education was associated with a steeper decline in MMSE with β = –1.00, SE = 0.43, p < 0.05 compared to those with lower education.

Conclusion This coordinated approach analysis revealed no consistent protection for those with higher education in terms of cognitive decline in preclinical stages of dementia, but showed an advantage in cognitive performance at the time of dementia diagnosis in half of the populations samples investigated. These results support only partially the theory that individuals with greater cognitive reserve as reflected in years of education, are better to cope with AD brain pathology without observable deficits in levels of cognitive performance or their rates of decline.