Accessible Requires Authentication Published by De Gruyter August 12, 2013

Identification of an important potential confound in CSF AD studies: aliquot volume

Jamie Toombs, Ross W. Paterson, Michael P. Lunn, Jenifer M. Nicholas, Nick C. Fox, Miles D. Chapman, Jonathan M. Schott and Henrik Zetterberg

Abstract

Background: Cerebrospinal fluid (CSF) amyloid β1-42 (Aβ1-42), total tau (T-tau) and phosphorylated tau181 (P-tau) are finding increasing utility as biomarkers of Alzheimer’s disease (AD). The purpose of this study was to determine whether measured CSF biomarker concentrations were affected by aliquot storage volume and whether addition of detergent-containing buffer mitigates any observed effects.

Methods: AD and control CSF was distributed into polypropylene tubes in aliquots of different volumes (50–1500 μL). Aβ1-42, T-tau and P-tau were measured with and without addition of Tween 20 (0.05%).

Results: Measured concentrations of Aβ1-42 increased two-fold with aliquot storage volume. A volume increase of 10 µL caused an Aβ1-42 increase of 0.95 pg/mL [95% confidence interval (CI) 0.36–1.50, p=0.02] in controls, and 0.60 pg/mL (CI 0.23–0.98 pg/mL, p=0.003) in AD samples. Following addition of Tween 20, the positive relationship between Aβ1-42 and aliquot volume disappeared. T-tau and P-tau were not significantly affected.

Conclusions: CSF aliquot storage volume has a significant impact on the measured concentration of Aβ1-42. The introduction of a buffer detergent at the initial aliquoting stage may be an effective solution to this problem.


Corresponding authors: Jamie Toombs, Department of Molecular Neuroscience, Institute of Neurology, University College London, London, UK, Phone: +44 20 34483553, E-mail: ; and Ross W. Paterson, Dementia Research Centre, Department of Neurodegeneration, Institute of Neurology, London, UK, Phone: +44 20 3448 3553, E-mail:

This work was supported by the Wolfson Foundation and the NIHR Queen Square Dementia BRU. The Dementia Research Centre in an Alzheimer’s Research UK Coordinating Centre. Gratitude is due to the laboratory staff at the Sahlgrenska University Hospital for providing the pooled CSF used in this study.

Conflict of interest statement

Authors’ conflict of interest disclosure: The authors stated that there are no conflicts of interest regarding the publication of this article.

Research funding: None declared.

Employment or leadership: None declared.

Honorarium: None declared.

References

1. Blennow K, Hampel H, Weiner M, Zetterberg H. Cerebrospinal fluid and plasma biomarkers in Alzheimer disease. Nat Rev Neurol 2010;6:131–44. Search in Google Scholar

2. Bartlett JW, Frost C, Mattsson N, Skillback T, Blennow K, Zetterberg H, et al. Determining cut-points for Alzheimer’s disease biomarkers: statistical issues, methods and challenges. Biomark Med 2012;6:391–400. Search in Google Scholar

3. Schoonenboom NS, Mulder C, Vanderstichele H, Van Elk EJ, Kok A, Van Kamp GJ, et al. Effects of processing and storage conditions on amyloid beta (1-42) and tau concentrations in cerebrospinal fluid: implications for use in clinical practice. Clin Chem 2005;51:189–95. Search in Google Scholar

4. Bateman RJ, Wen G, Morris JC, Holtzman DM. Fluctuations of CSF amyloid-beta levels: implications for a diagnostic and therapeutic biomarker. Neurology 2007;68:666–9. Search in Google Scholar

5. Bjerke M, Portelius E, Minthon L, Wallin A, Anckarsater H, Anckarsater R, et al. Confounding factors influencing amyloid beta concentration in cerebrospinal fluid. Int J Alzheimers Dis 2010;2010:986310. Search in Google Scholar

6. Sjogren M, Vanderstichele H, Agren H, Zachrisson O, Edsbagge M, Wikkelso C, et al. Tau and Abeta42 in cerebrospinal fluid from healthy adults 21–93 years of age: establishment of reference values. Clin Chem 2001;47:1776–81. Search in Google Scholar

7. Perret-Liaudet A, Pelpel M, Tholance Y, Dumont B, Vanderstichele H, Zorzi W, et al. Cerebrospinal fluid collection tubes: a critical issue for Alzheimer disease diagnosis. Clin Chem 2012;58:787–9. Search in Google Scholar

8. Hansson O, Zetterberg H, Buchhave P, Londos E, Blennow K, Minthon L. Association between CSF biomarkers and incipient Alzheimer’s disease in patients with mild cognitive impairment: a follow-up study. Lancet Neurol 2006;5:228–34. Search in Google Scholar

9. Conversion and calculations Aqua-Calc. Available from: www.aqua-calc.com. Accessed 21 February, 2013. Search in Google Scholar

10. Wiltfang J, Esselmann H, Bibl M, Smirnov A, Otto M, Paul S, et al. Highly conserved and disease-specific patterns of carboxyterminally truncated Abeta peptides 1-37/38/39 in addition to 1-40/42 in Alzheimer’s disease and in patients with chronic neuroinflammation. J Neurochem 2002;81:481–96. Search in Google Scholar

11. Bibl M, Esselmann H, Otto M, Lewczuk P, Cepek L, Ruther E, et al. Cerebrospinal fluid amyloid beta peptide patterns in Alzheimer’s disease patients and nondemented controls depend on sample pretreatment: indication of carrier-mediated epitope masking of amyloid beta peptides. Electrophoresis 2004;25:2912–8. Search in Google Scholar

12. Kaiser E, Schonknecht P, Thomann PA, Hunt A, Schroder J. Influence of delayed CSF storage on concentrations of phospho-tau protein (181), total tau protein and beta-amyloid (1-42). Neurosci Lett 2007;417:193–5. Search in Google Scholar

13. Carrillo MC, Blennow K, Soares H, Lewczuk P, Mattsson N, Oberoi P, et al. Global standardization measurement of cerebral spinal fluid for Alzheimer’s disease: an update from the Alzheimer’s Association Global Biomarkers Consortium. Alzheimers Dement 2013;9:137–40. Search in Google Scholar

Received: 2013-4-17
Accepted: 2013-7-17
Published Online: 2013-08-12
Published in Print: 2013-12-01

©2013 by Walter de Gruyter Berlin Boston