I believe what started all this is when Dad basically told the world to go to he... and he started sitting on his butt and watching TV. He kept saying “I’ve paid my dues” and would not do a damned thing. He even stopped reading.
Soon afterwards he had trouble walking and the rest of the problems started.
I’ll tell you what I’m going to do: study - - not just pleasure read.
My father’s sister read until she was 98 - - she died with a sharp mind and still had her wits about her. THAT is a lesson that will never leave me, unless I think that “I’ve paid my dues.”
While he is sitting there hand him a big ball of putty (size of a lemon) to work with in his hands. It stimulates certain parts of the brain.