Actually, I find all the jokes about "inevitable" memory loss depressing. Yes, it happens to many people, but it doesn't happen to everyone. The choices seem to be:
A. Eat right, get regular exercise and enough sleep, keep up your health and mental activities to minimize the changes of it happening and the severity if it does, or...
B. Live it up to the fullest, do whatever you want, and die before it happens to you.