For me yes, I'm not pretty, I'm not sporty, I can't draw or paint or play a musical instrument, but I am clever in a boring conventional pass school exams way.
That is totally intrinsic to who I am.
Maybe even more so to my incredibly clever, geeky, learn all there is to know about anything that crosses his path DH.
We would both be depressed and frustrated beyond measure if we had enough mental awareness to know we couldn't do what we used to.
Ageing is annoying, but a step change would be really hard.
In their quite different ways my DDs are their parents children.
I think my conventionally academic, very competitive DD2 would find it very very hard.
DD1 is dyslexic and already uses her very quick bright mind to work round her problems. So long as treatment left some of that intact she is far and away the most resilient of any of us.
What ever way you look at it, it's not something any of us would ever wish to face.