Many elderly people develop the brain lesions(損傷、機能障害), plaques, and tangled nerve cell fibers that are indicative of dementia and Alzheimer's disease, but not all exhibit the memory loss and confusion characteristic of these disorders. The findings, which come from a postmortem analysis of the brains of 38 Catholic nuns, also show that the remaining brain cells become larger in people with asymptomatic Alzheimer's disease, possibly preventing memory impairment(損傷、悪化).