
Cognitive Reserve in Action: Nun Study's Sister Mary Defies Alzheimer's Pathology
Sister Mary, a 101-year-old nun in the long-running Nun Study, showed near-perfect memory and reasoning before death despite a brain full of Alzheimer's plaques and tangles, illustrating cognitive reserve. The study’s hallmark finding was that autobiographies written in late adolescence, analyzed for idea density, predicted later dementia risk, with high idea density linked to lower risk. The research minimized lifestyle confounds, highlighting biology and lifelong mental activity as key factors and prompting a reevaluation of the amyloid-centric view of dementia. The brains of all 678 nuns continue to inform understanding of cognitive aging.













