... which kind of points to the indicator that "Alzheimer != Alzheimer", implying that too many diseases with the same side effects are categorized together?

A lot of virological and parasitical components have historically been wrongly associated with genetic markers, too. Toxoplasmosis parasite comes to mind.

[1] https://en.wikipedia.org/wiki/Toxoplasmosis

[2] https://en.wikipedia.org/wiki/Toxoplasma_gondii

Non-sequitur

Non-diagnostician

Point stands.

So does the lack of a model for Alzheimer’s,

and other chronic illnesses,

that the consumer-facing medical industry prefers to dismiss.