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 (<80 years; p=0.011) participants.
Conclusions: These initial findings not only confirm that platelet tau protein can be measured, but also
indicate that platelet tau measures merit further study as they may be useful in indicating early stages of
cognitive impairment. Further studies on larger number of participants are needed to confirm our findings.