Brain damage will make it increasingly difficult for the person in your care to ask for help. Part of the difficulty is in forming the thought and finding the right words. And partly it's a disappearing awareness of having any problems. What this means: You'll need to become an ever-better anticipator.
Avoid asking, "Are you ready to . . . " "Would you like me to . . . " "Are you hungry?" Instead, rephrase questions as matters of fact: "It's time to . . . " "Now let's . . . " "Your dinner is ready."
This way, you won't be told "no" automatically. Someone with dementia may say "no" even if he or she doesn't mean it, so by just diving in and helping, you're doing a double favor: addressing a need and also avoiding an unnecessary conversation that may go the way neither of you want.