A couple I work with got a new tv for Christmas (largest size made). the husband with moderate dementia, is bound and determined all of a sudden they need a new tv and a larger size. He just won't let it go. Nearly every day there is an argument between he and his wife about getting a new larger tv. I need ideas I can help them with to downplay his constant nagging about a new tv when they quite obviously already have a new one and the largest size and can't really afford it anyway. The one they have was given to them by their children. HELP!!
Talk this project over with his wife first. Tell her you'll deal with it so she doesn't have to. The point would be to give him something to think about and plan, to generate topics of conversation, to keep him interested. Don't argue with him about it. There can always be reasons why you can't act immediately ... the contractor for tearing out the wall is booked all season, the appliance store is closed for a family funeral, it is going to take a while to save that much money, etc. You aren't going to actually buy an unneeded tv -- just keep him occupied without fussing at his wife.
The exact nature of his dementia will make a difference in how to approach this. But I'd try for respectful interest in his ideas and no arguing.