Intact brain cells even in old age, that is possible? However, some conditions must be met for this to happen, simply keeping calm and waiting is definitely not suitable. What keeps my brain cells going is to stay active both physically and mentally.

Staying mentally active
To keep my brain cells fit, I read and write a lot, even doing crossword puzzles now and then is not wrong either. As a hobby text writer, I engage in the ideal activity to keep my mind busy. Writing texts on a wide variety of topics promotes creativity as well as memory.
Once written, it is hard to forget and writing almost every day is good training for the brain.

Do not remain physically inactive

Only in a healthy body...