Mine made to 97 clear (baked bread from scratch the same Autumn she turned 97) but then it was "what time is it" repeatedly. Since she had advanced macular degeneration, and her hearing was failing, I had to ask "didn't you hear me or don't you remember?" to which she said "I don't think I remember" and "that's not good, is it". After excluding Rx interactions and inadequate B12 (can mimic Alz), she was diagnosed with Alz Related Dementia and put on Aricept, later Exelon. After falling (and waiving off the EMT's with Levi Haines level toughness) the next day the pain set in, she ended up in nursing home, never to come out.
On my last visit where she was awake, she said "where's mom and don't tell me she's dead". (This was 2012, and her mother, born in 1889 died in 1982). I couldn't imagine how she couldn't remember or reason it through, but could anticipate a response. When she passed, she was 15 days short of 100. Her youngest sister became the first centenarian last October, after my grandmother and another sister both hit 99 and change.
Now my Mom's getting it, like my Dad and his sister. My Aunt was only in her 60's.