First, I am very sorry about your Dad. Dementia patients need to be treated with understanding and lots of love. Please make sure you don't run short of these two attributes. I was taught a little about Alzheimers in the science classes. He will sometimes think that he is something that he is not. Today he might think he is a senior pilot and tomorrow a technology expert. You don't need to argue with him all the time. Just accept and assure. My regards