This question is begging for an age-related tag and we don't seem to have one, and I wasn't sure how to word such a thing myself. I would personally use the term "Older users" but I'm sure there's a better and more accurate way to put it.
More generally is the issue of User Groups; experience, age, sex. These are often topics in UX and surely will be a common topic in our questions, but we don't seem to have any tags directly related to specific groups. I've never created a tag in SE before and I don't know which tags people believe would help so I thought I would ask here.
I've been doing some searching and neither the ACM or the SIGCHI conference seem to have a list of specific keywords for this sort of situation, so I can't decide. I have fonud a couple articles that use the terms "Older Users" (most frequently) and "Older Adults" (which I find less descriptive in a UX situation; the fact that they are a user is relevant, the fact that they are an adult is almost redundant). Currently I would suggest "Older Users", "Children" ("Child Users?") and perhaps "age-related design" or something similar for a more general tag.
Update: I created a tag
older-users for the question mentioned as that seems to be the most fitting or at least most common keyword used in academic articles from what I've seen.
An answer I got from a professor of Human Computer Interaction: "I don't think there are universally accepted terms. Yes, "children" and "older adults" tend to be most common, but it is best to try to be as specific as possible with the data or project you are dealing with."
Since we're talking tags rather than keywords for a specific, explicit research topic like a single paper, I think the "children" and "older adults" style tags are perfectly acceptable. After all while "Children ages 5-7" might be the explicit target of a single study/question, it's not very helpful as a tag if I'm searching for questions on designing for general age ranges.