cure for hiv, need more time- it's been 20 years
I know what you mean.
I've been having a low grade desire to make sure I didn't lose the knowledge level I spent years attaining.
In the past few days in fact I got a kick in the arse in the form of a situation coming up where a simple calculus based optimization would have made my job easier, but not quite remembering enough to be able to set up the problem quite right to solve.
My grandmother lived a long time with Alzheimer's. It was terrible. When I was a kid she was fine, but as I got older into my teenage years eventually she didn't know who I was (or anyone for that matter).
Physical and mental exercise supposedly decrease your odds. Do crosswords if nothing else.. Read more books. Jog or go the gym 3 or 4 times a week.