Platelet tau pattern correlates with cognitive status in Alzheimer's disease.

Platelets are major reservoirs of circulating amyloid-β and amyloid-β protein precursor (AβPP) and have been postulated as a reliable source for biological markers of Alzheimer's disease (AD). We have recently demonstrated that tau is also present in platelets, and that there are differences in the electrophoretic patterns of platelet tau forms in AD subjects with respect to controls. Here, we demonstrate that modifications in platelet tau forms occur independently of age in a broad population of 104 neurologically healthy individuals. More interesting, a strong correlation of platelet markers with the degree of cognitive impairment was evidenced in a group of 47 AD patients in comparison with 19 cognitive healthy subjects. In our series, platelet tau forms ratio had a sensitivity of 75.7% and specificity of 73.7%, respectively. We also found that platelet tau displays a significantly higher correlation with the presence of AD than the analyses of platelet AβPP.