I work with Alzheimer's/Dementia Patients as well. and one of the things I agree on is the time you spend with them is a plus. Keeping them active and seeing your face on a regular bases will gain that trust, with time your face will be familiar. one of the things I do is I Play a card game with them They seem to like "Black jack" it took them a whole month to learn the game but now thats all they want to to. Its an easy card game and the really enjoy it. Of course there is going to be those that cant add so you will have to hint the on whether or not to take a hit. Trust me Patience and care works great together.