Yes, and she's not the only one who is (edit: was) serving without being functional[1]. We need to start talking about upper age limits for public office. I believe it'd require a constitutional amendment, but I expect there's lots of support for it from all sides. I'd suggest 65 as a maximum age for being elected, which means one could serve to about age 71, for a six-year Senate term.
[1] This article is from six years ago. https://www3.bostonglobe.com/news/science/2017/10/11/congres...