alt Hacker NewsYou mentioned amyloid plaques. What about tau tangles? I thought Alzheimer's required both. If someone (or some dog, for that matter) has amyloid plaques but no tau tangles, is that Alzheimer's? If they have tau tangles but no amyloid plaques, what is it?
And what about the brains that show amyloid plaques, tau tangles, and Lewy bodies? Or plaques plus vascular lesions? At autopsy, most elderly brains show mixed pathology. Does that person have Alzheimer's plus Lewy body dementia plus vascular dementia? Three diseases? Or one brain failing in multiple correlated ways that we've artificially carved into separate categories?
It sounds like we have at least five different pathological markers that correlate with cognitive decline, often co-occurring, with inconsistent symptom mapping. What makes 'Alzheimer's' a disease rather than a region we've named in a high-dimensional space we don't really understand all that well?
> What makes 'Alzheimer's' a disease rather than a region we've named in a high-dimensional space we don't really understand all that well?
Nothing. I think it's sometimes in fact called a syndrome, not a disease per se. Since we don't really understand the mechanism of action, it remains more of a diagnosis by exclusion rather than anything else.