This is some personal opinion that I would bet the vast majority of Alzheimer's researchers would not actually agree with. The current consensus is that Alzheimer's is a particular disease, or a cluster of similar diseases.
I'm not saying your wrong, just that the level of confidence in your assertions is not warranted.
After spending years tracking through the genetics, conditions, lab work, research papers and seeing individuals years into the condition, this model is the best I have and explains everything I currently know. Why the cluster of conditions result in the same outcome, why some treatments help some folks, but not others.
But that is sort of the point of science, you take all the evidence you have and create a hypothesis and iterate as you get more evidence. If I find evidence that suggests something else then I will be happy to tweak or abandon this. My level of confidence comes from the existing evidence and lack of evidence otherwise.