Levels of total tau and tau protein phosphorylated at threonine 181 in patients with incipient and manifest Alzheimer's disease.

Cerebrospinal fluid tau protein levels are considered to be a promising marker for Alzheimer's disease (AD) and may facilitate early detection. Using the newly developed INNOTEST Phospho-Tau((181P)) kit examination of total tau and tau protein phosphorylated at threonine 181 (phospho-tau 181) revealed significantly (P<0.05) higher values in both patients with incipient and manifest AD than in controls. In patients with vascular dementia, phospho-tau 181 levels were not different from controls but were significantly lower than in patients with manifest AD. These findings suggest that total and phosphorylated tau protein may facilitate early detection and differential diagnosis of AD.