Your once-easy-going dad now thinks you’re stealing from him. Your ever-frugal mom is buying odd things she finds on the Internet. You know that these types of personality changes can be signs of dementia, yet when you offer to help, you're vehemently rebuffed. How do you convince your cognitively fragile parents to accept support? How hard do you push? There’s no easy answer, but there are steps you can take.