The clinical use of cerebrospinal fluid biomarker testing for Alzheimer's disease diagnosis: A consensus paper from the Alzheimer's Biomarkers Standardization Initiative

Background: Cerebrospinal fluid (CSF) biomarkers beta-amyloid 1-42 (A beta(1-42)), also expressed as A beta(1-42):A beta(1-40) ratio, T-tau, and P-tau(181P), have proven diagnostic accuracy for mild cognitive impairment and Alzheimer's disease (AD). How to use, interpret, and disclose biomarker results drives the need for standardization. Methods: Previous Alzheimer's Biomarkers Standardization Initiative meetings discussed preanalytical issues affecting A beta(1-42) and tau in CSF. This second round of consensus meetings focused on issues related to clinical use of AD CSF biomarkers. Results: Consensus was reached that lumbar puncture for AD CSF biomarker analysis be considered as a routine clinical test in patients with early-onset dementia, at the prodromal stage or with atypical AD. Moreover, consensus was reached on which biomarkers to use, how results should be interpreted, and potential confounding factors. Conclusions: Changes in A beta(1-42), T-tau, and P-tau(181P) allow diagnosis of AD in its prodromal stage. Conversely, having all three biomarkers in the normal range rules out AD. Intermediate conditions require further patient follow-up. (C) 2014 The Alzheimer's Association. All rights reserved.