Education and the risk for Alzheimer's disease: Sex makes a difference. EURODEM pooled analyses

The hypothesis that a low educational level increases the risk for Alzheime r's disease remains controversial. The authors studied the association of y ears of schooling with the risk for incident dementia and Alzheimer's disea se by using pooled data from four European population-based follow-up studi es. Dementia cases were identified in a two-stage procedure that included a detailed diagnostic assessment of screen-positive subjects. Dementia and A lzheimer's disease were diagnosed by using international research criteria. Educational level was categorized by years of schooling as low (less than or equal to 7), middle (8-11), or high greater than or equal to 12). Relati ve risks (95% confidence intervals) were estimated by using Poisson regress ion, adjusting for age, sex, study center, smoking status, and self-reporte d myocardial infarction and stroke. There were 493 (328) incident cases of dementia (Alzheimer's disease) and 28,061 (27,839) person-years of follow-u p. Compared with women with a high level of education, those with low and m iddle levels of education had 4.3 (95% confidence interval: 1.5, 11.9) and 2.6 (95% confidence interval: 1.0, 7.1) times increased risks, respectively , for Alzheimer's disease. The risk estimates for men were close to 1.0. Fi nding an association of education with Alzheimer's disease for women only r aises the possibility that unmeasured confounding explains the previously r eported increased risk for Alzheimer's disease for persons with low levels of education.