Joy,
The main thing to look for in a PA, I'm told, is reliability. You want
someone you can depend on. I am not sure how reliability relates to age. I
understand your concern about younger PA's, but if there is some way to check
on the person's stability, I would. Most universities now have something like
an Office for Students with Disabilities. This is the first place to start, I
believe, in searching for a PA.
Bobby