On one hand, I had a similar experience with my grandfather. He eventually couldn't even remember to speak English, he reverted to his childhood language. When we translated, he thought I was a childhood friend of his, not his grandson. It was awful
But sometimes he would be so lucid and remember everything. It was so awful thinking that "he is still in there" the idea of him choosing to end it and not have those last few times to talk.. I dunno
During one of those lucid times was the most deep and important conversation I ever had with him. He understood what was happening and it gave him the freedom (courage?) to talk about things he'd never talked to me about before. It was so important to me as a young man, I cannot imagine if he had signed an end of life form and I never got to see that side of him before he passed
Selfish of me I know. But still. Maybe this really just highlights how important it is for people to really talk to one another when they are alive