Simple solution: control your own finances.
What happens when a person is in the early stages of dementia and their family has them declared incompetent to handle their own finances?
Very good advice --- very good --- but sometimes not so simple. For instance, as soon as Terri Schiavo lost consciousness on the night of Feb 25, 1990, and for the next 15 years, her finances were controlled by her estranged husband, even after he set up housekeeping and had two children with another woman. March 31 is the 3rd anniversary of the day her "husband" finally got rid of her via court-ordered starvation.