I don't really think she is long for this world really. It is odd how fast she is loosing her mind and capabilities physically. Just a month ago it was a LOT different.
Sparkplug,
It does go quickly - my father (died 10 years ago) and my wife's mother (alive, in care) both had dementia but of different types. My dad went downhill for about 5 years slowly, but the last year was like falling down a cliff. He was cared for at home until the last year, but at a a great cost to my mother. In the end, it was either him into care or her collapsing. No arguement there - she is still going at 90years +, and admits that the move to care was a killer, but saved her. I know that you are heaps younger, but the toll is severe.
My wife's mother is a different case - really going downhill fast as she cannot care for herself & spends her days perpetually walking. Here, the emotional drain on the family was incredible, particularly as she became abusive and was perpetually running away.
In short, if I read your post right, please get your brother to get off his butt and get her into care. It is not the toll on the parent that is an issue (as long as the care facility is good) but it the toll on those around the parent. Those changes that you are seeing will get a l lot faster in coming and even more emotionally killing. I know.
Please take care - my thoughts are with you and especially for your family on this.
h9k