I guess I was lucky as far as my parents went. Though they both died of cancer and they were able to care for themselves almost to end.
Dad only lived for three weeks after his cancer was diagnosed though the doctors had told us he had months to live.
Mum had lung cancer and emphysema. She was only given a few months but managed to live almost three years staying in her own house right up to the day she died.
The only time I had to look after her was when she broke her hip about 6 years ago. I stayed with her for 2 months doing her housework, her shopping and cooking meals.
I can't imagine how I would have coped with a parent with dementia. I can't think of anyone in the family who has had it (maybe because the cancers seem to get us first).