So I do actually think they look like different people, that is a hell of a face lift. However just to play Devil's advocate knew someone who was very very mean, mean as a snake but he got brain cancer. The cancer destroyed his memories like a lot of them before it killed him though and he was a completely different person at the end. Exactly as his wife described him to be before life screwed him over about a billion times. So a mental decline can have personality changes but that presents a whole different set of problems because if he is declining mentally well he's declining mentally.