these preliminary findings suggest that platelet measures of the traditional biomarkers for AD are feasible in the periphery. The measures of platelet APP-N and Ig, in particular, merit further study in a larger cohort of AD and control subjects.

Previous inconsistencies in reported blood clusterin levels may be a result of underlying non-cognitive symptoms in people with AD. Our findings need now to be replicated in larger group of dementia subjects.

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.

We report a 16.5% increase in platelet immunoglobulin (Ig) content in subjects with Alzheimer's disease (AD) in relation to cognitively intact individuals (p = 0.021), whereas the plasma Ig levels were unaltered (p = 0.428). The upregulation of platelet Ig was not explained by age, duration of dementia, or degree of cognitive impairment. However, AD subjects treated with cholinesterase inhibitors (n = 21) had lower levels of platelet Ig (p = 0.009) than AD subjects not treated with anti-dementia drugs (n = 4) and similar to those of control subjects (n = 24; p = 0.069). The anti-dementia treatment did not influence the plasma Ig levels (p = 0.177). These preliminary findings require further confirmation in studies on larger number of AD subjects with various stages of cognitive impairment, and who would be assessed prior to initiation of and during cholinesterase inhibitor treatment.