paulflexes saidI've watched a few family members slowly deteriorate till death with Alzheimer's. In the early stages, it seems their mind comes and goes...having periods of clear thinking in between longer periods of dementia. During their clear moments, they know they have Alzheimer's.
If this ever happens to me, I will kill myself during one of my clear moments. After seeing the effects of it, I think that until a cure is developed, this would be a very legitimate case for assisted suicide. That is no way to live out your last days.
As every victim experienced AD differently, depending on various factors, if you see it in yourself and have that confirmed, do not count on it progressing how you've previously observed.
As to your plan B, a few things to keep in mind: being effected by the disease might lull you into accepting it, negating plan B. But also, even if you are already in the throws of it and have a lucid day, even if you are lucid enough to complete your thoughts, you might not be lucid enough to carry out those thoughts into action. So for you to assure your plan B, you'd have to be willing to give up possibly even some years of relatively healthy life before Alzheimer's takes hold, or suffer its torments.
As even growing older might change your mind on plan B, even before you get Alzheimer's ie it might not seem as scary then as it does now or every moment might seem more precious to you then than it does now, etc., and as dementia negates our ability to be absolutely assured that a person has not changed their mind, assisted suicide, I think, ought not be an option for victims of dementia.
My experience with that is by my mom who indicated that she'd had enough after she was no longer able to carry out the task herself, but I knew that if she hadn't dementia, she never would have asked me to risk my life in jail. So I knew that was not my mother in her right mind at the time and all I could do was watch her suffer and keep her as safe and comfortable as possible. I did not have the right to interfere with her life once she did not take that final step herself while she she had her window of opportunity.