How old is too old to fly?

I read a blurb in this morning's paper about age and cognitive ability.
It stated that tests have shown that as a person ages, his/her ability
to perform multiple tasks simultaneously diminishes. (Time to complete
the tasks increase.)
The example given is to stand on one foot while saying the alphabet
backwards.
Sounds like a test with a prize to be awarded at this summer's
rec.aviation.piloting party at AirVenture. Practice up if you plan to
attend. There will be a weighted point system depending on the beverage,
it's alcohol content and volume consumed prior to testing.