I'm in the same boat with my stepmom. She's going to be 80, but started showing severe dementia about 3 years ago (it was very rapid). She is also on Aricept and Namenda and she might as well be on sugar pills. I know the pharma industry is trying to come up with better meds, but until we get to the bottom of what causes Alzheimer's and other dementias it's a losing battle.

Human euthanasia is an incredibly thorny ethical issue, and also sort of a catch-22. An individual could, say, have a euthanasia order (were it legal, of course) but the family could put the kibosh on it, potentially. Same with DNRs, living wills, etc. There should never be some fixed age, anyway; it is a personal and family decision.