Platelet Tau Protein as a Potential Peripheral Biomarker in Alzheimer's Disease: An Explorative Study.

BACKGROUND: Cerebrospinal fluid (CSF) measures of tau and amyloid proteins have now been largely accepted to be a diagnostic tool to aid the clinical diagnosis of Alzheimer's disease (AD), but CSF is not routinely obtained in most clinical settings. There is a need, therefore, to uncover additional readily accessible peripheral biomarkers that will enable comprehensive detection of AD-specific proteins in blood and blood derivates. OBJECTIVES: Blood platelets contain proteins found in neuronal cell lines, including tau protein. Since tau protein is a characteristic of AD-neuropathology, platelet tau protein may be closely related to the central nervous process occurring in neurodegeneration. METHOD: Platelets from 25 AD and 26 control subjects were analysed for the microtubule-binding and C-terminal region, as well as two tau phosphorylation sites (Ser202/Thr205 and Thr181). RESULTS: Tau protein measures did not discriminate between AD and control individuals. However, subjects with MMSE 24-27 had elevated C-terminal end tau protein (p=0.049) compared to those with MMSE >27, whereas older AD subjects (>80 years) showed higher t-tau protein in comparison to younger AD (<80 years; p=0.009) and control (