Objectives: even though a great number of research studies have shown that high education has protective effects against dementia, some studies did not observe such a significant effect. In that respect, the aim of our study was to investigate and compare various operationalisation approaches of education and how they impact dementia risk within one sample.
Methods: data were derived from the Leipzig longitudinal study of the aged (LEILA75+). Individuals aged 75 and older underwent six cognitive assessments at an interval of 1.5 years and a final follow-up 15 years after the baseline assessment. We operationalised education according to different approaches used in previous studies and analysed the impact on dementia incidence via multivariate cox regression modelling.
Results: the results showed that whether education is identified as significant protector against dementia strongly depends on the operationalisation of education. Whereas the pure number of years of education showed statistically significant protective effects on dementia risk, other more complex categorical classification approaches did not. Moreover, completing >10 years of education or a tertiary level seems to be an important threshold to significantly reduce dementia risk.
Conclusion: findings suggest a protective effect of more years of education on a lower dementia risk with a particular critical threshold of completing >10 years of education. Further, the findings highlight that, when examining risks and protective factors of dementia, a careful consideration of the underlying definitions and operationalisation approaches is required.