Highly increased CSF tau protein and decreased beta-amyloid (1-42) in sporadic CJD: a discrimination from Alzheimer's disease?

The aim was to quantify tau protein and beta-amyloid (Abeta42) in the CSF of patients with sporadic Creutzfeldt-Jakob disease (CJD), Alzheimer's disease (AD), and controls. Double sandwich enzyme linked immunosorbent assays (ELISAs) were used for measurements. Tau was increased 58-fold in CJD and 3.5-fold in AD compared with controls, whereas Abeta42 was decreased 0.5-fold in both CJD and AD. A cut off level for tau protein at 2131 pg/ml successfully discriminated CJD from AD (100% specificity and 93% sensitivity). Tau protein concentration in CSF is probably an additional useful marker in differentiating CJD from AD.