it is good to tell him. In moms early stages. She still alwasy answered the phone. It has been and always was her house and she was the one who was surpose to answer the phone. But she did not remember who called or what was talked about . One of my brothers would just ask for me instead of talking to her. She started telling every one that he did not want to talk the her. Or no one called her anymore they all just want to talk to me. So she rememberd that. Tell him everything. He will remember . You just might not be able to tell but it is in his memory somewhere. I believe that.