My mum has also been much happier since developing Alzheimer's. She was diagnosed in 2009 but has often been described by doctors and social workers as pleasantly confused. She has had her moments of course, like when she has her pads changed, but it seems that any unhappiness is in response to something and not her general mood. I think in many ways it has made things much smoother than they might have been otherwise. She just seemed to forget her worries and respond positively to most things, especially music. She was even happy when she was in the early stages and her favourite brother died. A moment I was dreading, she just smiled and said oh well he had a good life. I know before she got Alzheimer's she would have never reacted like that and been so upset. Best wishes.