Advantages and disadvantages of the use of the CSF Amyloid β (Aβ) 42/40 ratio in the diagnosis of Alzheimer’s Disease

Research output: Contribution to journalReview article


The cerebrospinal fluid (CSF) biochemical markers (biomarkers) Amyloidβ 42 (Aβ42), total Tau (T-tau) and Tau phosphorylated at threonine 181 (P-tau181) have proven diagnostic accuracy for mild cognitive impairment and dementia due to Alzheimer’s Disease (AD). In an effort to improve the accuracy of an AD diagnosis, it is important to be able to distinguish between AD and other types of dementia (non-AD). The concentration ratio of Aβ42 to Aβ40 (Aβ42/40 Ratio) has been suggested to be superior to the concentration of Aβ42 alone when identifying patients with AD. This article reviews the available evidence on the use of the CSF Aβ42/40 ratio in the diagnosis of AD. Based on the body of evidence presented herein, it is the conclusion of the current working group that the CSF Aβ42/40 ratio, rather than the absolute value of CSF Aβ42, should be used when analysing CSF AD biomarkers to improve the percentage of appropriately diagnosed patients.


  • Oskar Hansson
  • Sylvain Lehmann
  • Markus Otto
  • Henrik Zetterberg
  • Piotr Lewczuk
External organisations
  • Skåne University Hospital
  • University of Montpellier
  • University of Ulm
  • University College London
  • University of Gothenburg
  • University Hospital Erlangen
  • Medical University of Bialystok
  • Montpellier University Hospital
  • Friedrich-Alexander University Erlangen-Nürnberg
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurology


  • Alzheimer’s Disease, Amyloidβ Peptides, Aβ42/40 ratio, Biomarkers, Cerebrospinal Fluid
Original languageEnglish
Pages (from-to)1-15
Number of pages15
JournalAlzheimer's Research and Therapy
Issue number1
Publication statusPublished - 2019 Apr 22
Publication categoryResearch