Cerebrospinal fluid amyloid β42/phosphorylated tau ratio discriminates between Alzheimer's disease and vascular dementia

Abstract

Background. The differentiation of Alzheimer's disease (AD) from vascular dementia (VaD) is hampered by clinical diagnostic criteria with disappointing sensitivity and specificity. The objective of this study was to investigate whether cerebrospinal fluid (CSF) levels of total tau protein (t-tau), amyloid β42 protein (Aβ42), and tau phosphorylated at threonine 181 (p-tau181) are useful biomarkers to distinguish AD patients from VaD patients. Methods. We measured CSF levels of p-tau 181, Aβ42, and t-tau in 86 patients with a clinical diagnosis of AD or VaD and in 30 control participants. Results. Optimal differentiation between AD and VaD was achieved by using the ratio of the CSF levels of Aβ42 and p-tau181 (Q Aβ42/ p-tau) with sensitivity, specificity, positive and negative predictive values all ≥85%. Conclusions. Our results support further efforts to prospectively validate the use of Q Aβ42/p-tau as a biomarker to discriminate between AD and VaD. Copyright 2006 by The Gerontological Society of America.