Platelet immunoglobulin and amyloid precursor protein as potential peripheral biomarkers for Alzheimer's disease: findings from a pilot study

Methods: twenty-five subjects with a clinical diagnosis of AD and 26 control participants were assessed for cognitive and behavioural functioning. Platelet measures of amyloid protein precursor (APP), tau protein, clusterin, alpha-synuclein and immunoglobulin (Ig) were measured. Linear regression analysis for platelet proteins and cognitive and behavioural status were determined, and receiver operating characteristic (ROC) curves created to assess the discriminating power of each biochemical parameter between AD and control groups. Results: both AD and control subjects had similar platelet levels of measures platelet proteins, with the exception of slightly elevated Ig levels in AD subjects (P = 0.052). The latter were not related to increasing age, or extent of cognitive impairment. APP-N measures were negatively correlated with cognitive scores. Conclusion: 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.