I originally qualified as a PPL in a DH82 at 28, after about 20 hours flying (experienced glider pilot). I learned non radio, and the sylabus was a lot simpler then.
After a break of 23 years with no flying, I re-qualified in my late 50's and am not aware that age had any impact on the learning process. I certainly sailed through the far more extensive exams and the only learning problems I had were that both my instructor and I assumed too much that I could already do most things and, as long as I did them, this assumption prevailed. It was only after qualifying that I really discovered that I had not really re-learned how to land properly, when I tried to check out on a different aeroplane.
Certainly, as I have got older, I seem to more frequently forget names of people and places but, so far, I seem to remember all essential information for flying. As one of my school teachers used to say, "You remember those things that you want to".