In the setting of Alzheimer’s and other neurodegenerative diseases, do T cells make things better, or worse? A simple answer just won’t do—it likely depends on the type of T cells, where they are in ...

This article was produced in partnership with Regeneron by Scientific American Custom Media, a division separate from the magazine’s board of editors. In the long-running quest to improve on ...

When cells experience enough chronic stress, they can stop dividing permanently. In this state of cellular limbo, known as replicative senescence, cells remain alive but no longer proliferate.