Age-dependent inverse correlations in CSF and plasma amyloid-β(1-42) concentrations prior to amyloid plaque deposition in the brain of 3xTg-AD mice

Amyloid-beta (A beta) plays a critical role as a biomarker in Alzheimer's disease (AD) diagnosis. In addition to its diagnostic potential in the brain, recent studies have suggested that changes of A beta level in the plasma can possibly indicate AD onset. In this study, we found that plasma A beta(1-42) concentration increases with age, while the concentration of A beta(1-42) in the cerebrospinal fluid (CSF) decreases in APP(swe), PS1(M146V) and Tau(P301L) transgenic (3xTg-AD) mice, if measurements were made before formation of ThS-positive plaques in the brain. Our data suggests that there is an inverse correlations between the plasma and CSF A beta(1-42) levels until plaques form in transgenic mice's brains and that the plasma A beta concentration possesses the diagnostic potential as a biomarker for diagnosis of early AD stages.