An autopsy-verified study of the effect of education on degenerative dementia

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Abstract
A longitudinal study of the relationship between education and age of onset, rate of progression and cerebral lesion burden in a series of autopsy-confirmed demented patients with clinical and 6-monthly psychometric follow-up and autopsy was carried out. The study was conducted at the London Health Sciences Centre University Campus of the University of Western Ontario on 87 patients with pathologically confirmed Alzheimer's disease (60), dementia with Lewy bodies (11) or dementia with Lewy bodies plus Alzheimer's disease (16). Their educational attainment was classified as below high school, high school or above high school, and was similar to that of the age-adjusted general Ontario population. The age of onset of dementia, age at death, progression of cognitive decline, amount of neurodegenerative changes (senile plaques, neurofibrillary tangles and Lewy bodies) and cerebrovascular lesions (infarcts, lacunar state and white matter rarefaction) were assessed. Less educated patients became demented later and died later, but cognitive function declined at the same rate in all educational groups and there was no difference in the burden of neurodegenerative lesions between them. However, the less educated patients had more cerebrovascular lesions. It can be concluded that higher education does not modify the course of Alzheimer's disease, but lower education relates to the occurrence of cerebral infarcts. Our results suggest that a `brain battering' model related to the higher prevalence of small vascular lesions in less educated individuals may explain their increased risk of dementia described by epidemiological studies better than the prevalent `brain reserve' hypothesis.