AFAIK nobody has a clear idea of which cognitive abilities degenerate due to normal ageing AND respond to exercise (other than N-Back helping short term memory,

AFAIK nobody has a clear idea of which cognitive abilities degenerate due to normal ageing AND respond to exercise (other than N-Back helping short term memory, perhaps). I'd start by looking at the standard components of cognition. Start with the sub-metrics in the Wechsler IQ test. See what specific mental skills you might want to maintain or improve. https://en.wikipedia.org/wiki/Wechsler_Adult_Intelligence_Scale https://en.wikipedia.org/wiki/Wechsler_Adult_Intelligence_Sc... Then design your own tests to assess each skill and your own mental exercises to see if you can strengthen your mental muscles. Positive feedback is your best guide, IMHO.