I try to comfort myself that perhaps, because of my dads ALZ, he at least didn't have to realize he was dying. A former girlfriend's father and mother both died of cancer, and unfortunately in that case they knew what their fate was and it was very scary for them. What about ALZ patients? Are they cognizant enough to know what their condition means?
I was with him when he died and it was peaceful. His breathing got shallower and slower, then stopped.
Perhaps you can take comfort from my experience.