I dont know everything about this and dont know the details, but I can tell about a couple of incidents that I have experienced.
Mum was adamant that there was nothing wrong with her and wouldnt go to her GP, then didnt go to any of her appointments at the memory clinic and point blank refused any help. Social Services phoned her up (!) to talk to her and she told them that she did all her own shopping, cooking, laundry, gardening etc etc, when in reality she was doing none of it. She was not eating properly, or drinking, or washing, or changing her clothes and I was pulling my hair out. I contacted SS and because she had not been assessed as lacking capacity they had to assume that she did have capacity, so as she had refused any help they wouldnt do anything.
Eventually, the crisis came. She had a TIA and ended up in hospital. While she was in there her dementia became impossible to ignore. She had a capacity test and was found to have lost capacity and they said it was not safe to send her home, even with carers - so she was placed in a care home and has been there ever since.
The other incident I know about (but not in so much detail) concerns a friend of mine whose husband has fronto-temperal dementia and he became
very aggressive. She did not want him to go into a home (and he didnt want go either) even though friends (including me) said that we thought that he should. Eventually he trashed the kitchen and hit her with his stick, fracturing her collar-bone. Ambulance and police we called and he got sectioned. He went first to a special unit and then to an EMI dementia home where he still is.
I dont know if any of this helps and I expect that someone else will be along who knows more than me.