Urban residence and higher education do not protect against cognitive decline in aging and dementia : 10-Year follow-up of the Canadian Study of Health and Aging

The construct of cognitive reserve has primarily been defined in terms of a single proxy measure, education. There may, however, be alternative, potentially additive, proxy measures of cognitive reserve, such as rural or urban residence. Using a large sample of 10,263 older Canadians, ranging in age between 64 and 99years (mean age=75.7years, SD=7.1), residents of rural and urban areas were compared using the Modified Mini-Mental State (3MS) examination as a dependent variable. Within this sample, subsamples of demented and non-demented individuals were investigated. The 3MS data were analyzed using a linear mixed model with years of education and residence as proxies of cognitive reserve and time of testing (linear and quadratic) as a within-groups variable. All predictor variables in the model (i.e., gender, age, education, residence, and time of testing) had a significant impact on cognitive functioning. The results showed that, although urban residents and higher educated individuals performed better than rural residents and lower educated individuals at baseline, these performance benefits were nullified at 10-year follow-up. The disappearance of these initial performance benefits suggests that urban dwellers and higher educated individuals are not protected against age-related cognitive decline. Thus, no support was found for the cognitive reserve hypothesis.