The Role of Aging in Alzheimer’s Disease

Abstract

Cognitive function in humans declines in essentially all domains starting in the late 50s, and neurodegeneration and dementia seem to be inevitable in all but a few of those who survive to very old age. While age-related cognitive dysfunction and Alzheimer’s disease in humans are clearly distinct entities and seem to affect different brain regions, both show the telltale molecular and cellular changes that characterize tissue aging including abnormal proteostasis, loss in stem cell activity, and inflammation. Adding to the challenge of differentiating the two, Alzheimer’s disease is thought to begin up to 20 years before it manifests clinically and, accordingly, there is significant overlap between brain aging and the disease based on structural and functional brain imaging. This chapter will highlight commonalities and emphasize divergences between “normal” brain aging and Alzheimer’s disease and discuss novel approaches to understand the link between the two.