I changed a character's name halfway through a book once and that was when I was young enough for my brain to have not yet turned to mush.
Also, there has been some progress on the Alzheimer's front. No cures, yet, but I think they've found something like three different types which would mean different treatment plans for each. And there's stuff that has been found helpful in slowing progression. I think eating nuts is supposed to be good as well as keeping your mind active. Walking too. I think there was something about walking.
I play games in the mornings to help keep my mind exercised - picture puzzles, Fitz, and the hardest solitaire game on windows 10. Arthritis makes walking a challenge and I fall easily. I know they are working on developments, but at this point (age) 74, do I want to spend my money on doctor bills for that problem? It's expensive enough when we get old just to manage pain. Decisions, decisions.
Yes, it's easy to run up a pretty big bill--but it might be worth it. Not only are there different types of Alzheimer's, but there are other potential causes of memory loss, some of which are easily treatable.
I thought my dad was in the early stage of Alzheimer's, but he turned out not to be. The problem in his case was that he had lung issues and wasn't getting enough oxygen. With proper supplemental oxygen, what I thought were Alzheimer's symptoms disappeared within a week.
Even things as simple as stress or irregular sleep patterns can contribute to memory loss. Because stress can be a contributing factor, worrying too much about having Alzheimer's can actually make it seem more like you do. (Self-fulfilling prophecy.) One of my friends was in a highly stressful situation and appeared to be in the first stages of some kind of dementia. When the stress was reduced, the symptoms vanished.
I think the diagnosis of Alzheimer's is still a diagnosis of exclusion. Since the only way to be sure is to dissect your brain, doctors have to rule out other things it could be through testing. However, sometimes people get lucky, and the cause is discovered without having to go through a huge number of tests.