A cytometric bead array for the measurement of plasma biomarker levels in patients with Alzheimer's disease.

Identifying plasma biomarkers for Alzheimer's disease (AD) has garnered strong interest. In this study, a cytometric bead array (CBA) method for measuring the levels of amyloid-β (Aβ) peptides and phosphorylated tau (P-tau) was evaluated. Fifty patients with cognitive impairment (CI) and 22 cognitively unimpaired (CU) controls were recruited. CI patients were classified into Aβ + and Aβ - groups according to amyloid positron emission tomography (PET) scan results. Biomarker levels in the plasma of all participants and in the cerebrospinal fluid (CSF) of 28 CI patients were measured via CBA. Plasma P-tau181 levels were greatest in the Aβ + CI group and showed excellent performance in differentiating Aβ + CI patients from CU controls. The plasma and CSF levels of P-tau181 were correlated with each other and had similar diagnostic performance for distinguishing between Aβ + CI patients and Aβ- CI patients. Overall, CBA is a potential cost-effective method for measuring plasma biomarkers, particularly P-tau181, in AD patients.