Chris used to say to me - you think you know where you have set the line, but as you progress it moves too.
I call that 'moments of lucidity' that he had with FTD and totally agree on that point!
Max, and everyone, it is hard for any one person to say where the line should be drawn to signify that quality has ended because people tend to talk about it in milestones. eg if I need a peg or a pwc or whatever.
To me this has less to do with the question than does the INTERNAL side of things.
This is really difficult with text! Let me say this - quality is an internal state of being, but it is affected by the external state too.
I can only use the situation we were in to provide examples that I hope will make sense to others in a different situation.
Now for my Chris who had worked for so many years in hospitality, losing the ability to speak and swallow first was pure hell.
Chris insisted on attempting to speak as long as possible, resisted learning to use technology even though I purchased good quality technology for him very early so he could learn to use it before he fully needed it. He instead insisted on attempting to speak, and relying on me, and requiring me to stick beside him all the time and interpret for him. The energy it required from him was enormous, the conversations were painfully slow and often confusing, and he withdrew from people more and more and more.
He constantly blamed it all on the fact that all other people were lazy and couldn't be bothered trying to understand him, or treated him like he was mentally impaired. If only they would get over themselves it wouldn't be so bad ...
For me, losing the ability to speak and swallow would be devastating, but I would have put my energy into all the technology I could find out about to use for communication and learn as much as I could about communicating effectively with that technology. Just as I've been active here on this forum, I would have been actively communicating with people, just differently, and it would have taken less of my energy to do so. This means I could have had better quality communication, using less energy. INTERNALLY I would have had better quality of life as I could communicate.
Of course, my ability to use technology would have continued to decline.
Chris would tell me that it was just too hard to even try to communicate.
Now, this is just an example, please don't all take every tiny point too literally. We are all different, and for someone else the biggest issue may be mobility, continuing to work or something else.
Tracy here is amazing in how she has continued to work with children when many others would have given up. But she hasn't done it by 'fighting' the disease and being stubborn. She has done it by recognising her limitations and working with others to overcome them. One day Tracy will have to stop working, but I will bet anything that she will have all the wonderful memories of how long she continued to work for, in a quality way, and how it has touched the lives of so many.
Max has been able to change his work role to still contribute something of great value to his employer, but again recognising his limitations and working with others to overcome.
BigMark modified his motorbike so he could continue to ride longer with safety.
For Chris, it was just plain draining, unproductive and embarrassing and not only did he withdraw more and more, but people didn't really want to come and spend time with him because they found it so hard and embarrassing.
Trying to put it 'in a nutshell'
To me, quality of life means firstly working out what is most important to you. Then working out how much energy you are using on the things that are not so important, and getting assistance with those things (dressing, showering, walking eg), thus preserving as much energy as possible for the important things.
Gosh, I've got all this in my head and it seems clear, but the more I'm writing here the more I wonder if I'm making sense at all.
If not, it might at least be giving 'food for thought' and you can all debate it