Yet if you look at people who develop the clinical syndrome of dementia, especially later in life, yes, they have amyloid in the brain but they also have other pathologic entities — vascular disease; synucleinopathies [
insoluble fibrils of the normally soluble protein, alpha - synuclein]; a tauopathy [which is marked by disease - inducing, insoluble tangles of another protein, tau].
Amyloid - β 42 (Aβ42) has a strong ability to oligomerize to form diffusible oligomers as well as larger polymers called
fibrils that form
insoluble amyloid plaques, a major hallmark of AD.