Lived with a family member who had it. Within 3 months it went from tolerable to live there (in the beginning, she would ask me to remind her of my name, every 10 minutes) to unbearable (every time I went to sleep, within an hour or two, she'd be pounding on my door, screaming, telling me to get out of her house - she had no idea who I was, thought I had broken in).
I moved out; she was moved to a nursing home; she died a few months later.
I could never recommend moving in, after that. Your mum is going to need a tremendous lot of help no matter what, but are you prepared to sacrifice your entire personal life and become her 24/7 live-in nurse, doctor, groomer, chef, and memory assistant? What she may end up needing is full-time around-the-clock care. If you move in, you could be saying goodbye to any other part of your life, for as long as she lives.