What does a normally aging brain look like? Are diseases of aging such as Alzheimer’s inevitable?
Only 40 years ago it was widely believed that if you lived long enough, you would eventually experience serious cognitive decline, particularly with respect to memory. The implication was that achieving an advanced age was effectively equivalent to becoming senile—a word that implies mental defects or illness. As a graduate student back then, I was curious why such conclusions were being drawn about the elderly. I had only to look as far as my own great-grandmother and great-aunt to begin questioning the generalization. They lived to 102 and 93, respectively, and were exceptionally active and quick-witted enough to keep us twenty somethings on our toes. A closer look at the literature didn’t give me any confidence that either the biological basis of memory or how it might change with age was well understood. Many discoveries made in the years since have given us better tools to study memory storage, resulting in a major shift away from the view of “aging as a disease” and towards the view of “aging as a risk factor” for neurological diseases. So why do some people age gracefully, exhibiting relatively minor—and at worst annoying—cognitive changes, while others manifest significant and disabling memory decline? Answers to these questions are fundamental for understanding both how to prevent disease and how to promote quality of life.