AllanS, tell your M.D. it doesn't have to be so! MY dad turned 83 this week and a few years ago set himself the goal of learning several new songs per month. Sure he can recall ones from 60-70 years ago easily, but he also recalls the more recent ones. The only cheatsheet he carries is the names of the songs listed according to how he plans to perform them.

I grew up playing violin in orchestra, reading music, but also listening to mom and dad play for dances, and we kids singing along. If I try to play something trad from the sheet music, I find my ear takes over, if there are any variations, and I just forget the music and play what my ear remembers.