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

Tau and beta -amyloid (1-42) (A beta 42) are two independent markers for th e early diagnosis of Alzheimer's disease (AD). In the present study, bioche mical 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 pa tients with AD (n=80) or DLB (n=43) using the HT7-AT270 assay (prototype ve rsion). 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 discriminato ry power of total tau with that of phospho-tau. The area under the curve (A UC) 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 differentia tion between AD and DLB.