https://www.wired.com/story/overexcited-neurons/

A thousand seemingly insignificant things change as an organism ages. Beyond the obvious signs like graying hair and memory problems are myriad shifts both subtler and more consequential: Metabolic processes run less smoothly; neurons respond less swiftly; the replication of DNA grows faultier.

Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research develop­ments and trends in mathe­matics and the physical and life sciences.