Context

The notion of cognitive reserve or intellectual capacity offering protection for cognitive function arose from early observations of education's apparent protective effect against Alzheimer's disease.1 Observed differences in parietotemporal perfusion by the education level among patients with Alzheimer's disease offered some biological evidence to support the notion.2 Subsequently, the cognitive reserve hypothesis was published,3 and a number of studies have offered support for this theory. However, the issue of reverse causality has not been resolved. Reverse causality in this context means either that individuals suffering from latent or early disease tend to withdraw from participation in cognitive activities, or that individuals with lower …