75-80 years old people as they studied are really not that old to have significant issues with cognitive functions, of course physical functions get hit.
My father who will be soon 70 is doing hiking in mountains pretty much all summer, while his mother when she was in her 80s took care about her house, garden and animals and only in the very end with tumor on brain experienced very fast decline.
I'd say, just stay active, don't sit at home all the time, if you want to stay in good physical condition and socialize to keep good cognitive functions.
My father who will be soon 70 is doing hiking in mountains pretty much all summer, while his mother when she was in her 80s took care about her house, garden and animals and only in the very end with tumor on brain experienced very fast decline.
I'd say, just stay active, don't sit at home all the time, if you want to stay in good physical condition and socialize to keep good cognitive functions.