Detection of Alzheimer's disease amyloid beta 1-42, p-tau, and t-tau assays

Alzheimers Dement. 2022 Apr;18(4):635-644. doi: 10.1002/alz.12406. Epub 2021 Jul 26.


Introduction: We aimed to provide cut points for the automated Elecsys Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers.

Methods: Cut points for Elecsys amyloid beta 42 (Aβ42), total tau (t-tau), hyperphosphorylated tau (p-tau), and t-tau/Aβ42 and p-tau/Aβ42 ratios were evaluated in Mayo Clinic Study of Aging (n = 804) and Mayo Clinic Alzheimer's Disease Research Center (n = 70) participants.

Results: The t-tau/Aβ42 and p-tau/Aβ42 ratios had a higher percent agreement with normal/abnormal amyloid positron emission tomography (PET) than the individual CSF markers. Reciever Operating Characteristic (ROC)-based cut points were 0.26 (0.24-0.27) for t-tau/Aβ42 and 0.023 (0.020-0.025) for p-tau/Aβ42. Ratio cut points derived from other cohorts performed as well in our cohort as our own did. Individual biomarkers had worse diagnostic properties and more variable results in terms of positive and negative percent agreement (PPA and NPA).

Conclusion: CSF t-tau/Aβ42 and p-tau/Aβ42 ratios are very robust indicators of AD. For individual biomarkers, the intended use should determine which cut point is chosen.

Keywords: Alzheimer's disease; CSF; biomarkers; cut point.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease* / cerebrospinal fluid
  • Alzheimer Disease* / diagnostic imaging
  • Amyloid
  • Amyloid beta-Peptides* / cerebrospinal fluid
  • Biomarkers / cerebrospinal fluid
  • Humans
  • Peptide Fragments / cerebrospinal fluid
  • tau Proteins / cerebrospinal fluid


  • Amyloid
  • Amyloid beta-Peptides
  • Biomarkers
  • Peptide Fragments
  • tau Proteins