CSF phosphorylated tau is a possible marker for discriminating Alzheimer's disease from dementia with Lewy bodies

Tau and beta -amyloid (1-42) (A beta 42) are two independent markers for the early diagnosis of Alzheimer's disease (AD). In the present study, biochemical markers were validated as tools for differential diagnosis between AD and dementia with Lewy bodies (DLB). Tau, A beta 42 and phosphotau (181P) were measured in cerebrospinal fluid (CSF) from controls (n=40) and from patients with AD (n=80) or DLB (n=43) using the HT7-AT270 assay (prototype version). In comparison with AD, in DLB no differences were found for A beta 42 and lower phospho-tau. ROC analysis was used to compare the discriminatory power of total tau with that of phospho-tau. The area under the curve (AUC) amounted to 0.782 +/-0.048 (mean +/- SE) for tau and to 0.839 +/-0.042 for phospho-tau (p = 0.039) for differentiation of AD from DLB. The present results indicate that CSF phospho-tau may be a good marker for differentiation between AD and DLB.