My mother-in-law, 86, believes that all the food at the memory care facility she lives in is poisoned. She will only eat food that a family member brings to her, and even then only fast food that is still in the packaging (like a McDonald's hamburger). She never had any delusions or psychosis before. Is this the dementia or is there something else going on? We can't really afford to keep buying her fast food, but I'm afraid if we don't she will starve herself.