de Leon MJ, Segal S, Tarshish CY, DeSanti S, Zinkowski R, Mehta PD, Convit A, Caraos C, Rusinek H, Tsui W.
Longitudinal cerebrospinal fluid tau load increases in mild cognitive impairment.
Neurosci Lett. 2002 Nov;333(3):183-6.
Cross-sectional cerebrospinal fluid (CSF) levels of tau and amyloid (A) beta (b) are of diagnostic importance for Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, most longitudinal studies of tau fail to demonstrate progression. Because predominantly brain-derived proteins such as tau, have higher ventricle to lumbar ratios, we hypothesized that adjusting for the ventricular enlargement of AD would correct for the dilution of tau, and improve detection of longitudinal change. Ab which is not exclusively brain derived, shows a ratio b40, and Ab42. In cross-section, MCI patients showed elevated Ptau231 and Ab40 levels, and greater ventricular volumes. Longitudinally, only after adjusting for the ventricular volume and only for Ptau231, were increases seen in MCI. Further studies are warranted on mechanisms of tau clearance and on using imaging to interpret CSF studies.