Thing is, it doesn't happen like flicking a switch, it's progressive and tricky to process as a caretaker.
I'm seeing this right now with a close friend and her 83yo mother.
It's seriously damaging to my friend, and no amount of my reasoning with her seems to help her process her mother's cognitive decay...
...and it leaves me defeated also, I don't have the tools to really be of true help.
As far as I'm concerned I am my mind. If my mind is gone my body doesn't matter, please don't waste effort in caring for it.