I used to be interested in the effect of aging on cognition in an objective sense, but now, at age 84, the issue becomes very close at hand. I frequently challenge my memory to be sure that I'm not losing it.
Forty years ago I had no real backing for my intuition that exercise is the magic bullet, the universal panacea. Now even the brain is targeted for both preventive and therapeutic approaches to cognitive decline.
As we grow up, we learn patience and self-control, and we grow more adept at our favorite hobbies. And our brains are gaining skills, too: As the birth of new neurons slows down, those cells are learning to communicate more efficiently.