Wrote up my current systems understanding here https://metamagic.substack.com/p/the-alzheimers-equation, but it makes clear why treatments that target only one variable are mathematically doomed to fail to work on everyone and why there will never be a single "cure". It explains without needing to read 10,000 papers why we keep getting research talking about treatment X helps in some, but not all cases or symptom Y is associated in some, but not all, etc.