Plasma amyloid beta-peptide 1-42 and incipient Alzheimer's disease

Mutations in the amyloid precursor protein and presenilin 1 and 2 genes res ult in elevated plasma levels of the amyloid beta-peptide species terminati ng at amino acid residue 42 (A beta 1-42). In a longitudinal study of unrel ated elderly individuals, those who subsequently developed Alzheimer's dise ase had higher plasma levels of A beta 1-42 at entry than did those who rem ained free of dementia. The results indicate that elevated plasma levels of the released A beta peptide A beta 1-42 may be detected several years befo re the onset of symptoms, supporting that extracellular A beta 1-42 plays a n important role in the pathogenesis of late-onset Alzheimer's disease.