Structural differences in amyloid-β fibrils from brains of nondemented elderly individuals and Alzheimer's disease patients

Significance Alzheimer's disease (AD) patients develop amyloid deposits, containing amyloid-β (Aβ) fibrils, in their brain tissue. Although amyloid is a likely contributor to AD dementia, similar amyloid loads occur in some nondemented elderly individuals. Molecular structures of Aβ fibrils are known to be variable. We, therefore, investigate whether structures of Aβ fibrils derived from cerebral cortical tissue of nondemented elderly subjects differ from structures from AD patients. We find statistically significant, but subtle, differences between NMR spectra of Aβ fibrils from nondemented elderly subjects and analogous spectra of fibrils from AD patients. Thus, similar structures develop but with different relative populations on average. Other factors may be primary determinants of cognitive status in individuals with high amyloid loads.