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Tau/Aß42 Cerebrospinal Fluid Test

Last updated Sept. 14, 2018

The Tau/Aß42 Cerebrospinal Fluid Test is a test to assess the levels of tau and free-floating Aß42 proteins in cerebrospinal fluid. It is used to diagnose Alzheimer’s disease.


What are the other Names for this Test? (Equivalent Terms)

  • Alzheimer’s Disease Biomarkers CSF Test
  • Tau Protein and ß-Amyloid 42 Peptide CSF Test
  • Tau/Aß42 CSF Test 

What is Tau/Aß42 Cerebrospinal Fluid Test? (Background Information)

  • Tau and ß-amyloid 42 (Aß42) are proteins that form the tangles and plaques responsible for causing Alzheimer’s disease
  • Alzheimer’s disease (AD) is a disorder of the nervous system. It is the most common cause of dementia in elderly individuals. Dementia is characterized by memory disorders, personality changes, and impaired reasoning
  • Alzheimer’s disease may appear in old age as a result of gradual progression. Alternatively, AD may be early in onset and appear suddenly. Regardless of the onset, the two characteristics defining AD are amyloid plaques and brain tangles
  • Amyloid plaques result from accumulations of Aß42, a protein of the cerebrospinal fluid (CSF). Individuals with amyloid accumulations possess less free-floating Aß42 in their CSF, because it has clumped together in plaques
  • Brain tangles are caused by defects in the tau protein that cause it to aggregate. It is believed that the number of brain tangles is related to the severity of Alzheimer’s disease
  • The Tau/Aß42 Cerebrospinal Fluid Test is a test to assess the levels of tau and free-floating Aß42 proteins in cerebrospinal fluid. It is used to diagnose Alzheimer’s disease

What are the Clinical Indications for performing the Tau/Aß42 Cerebrospinal Fluid Test?

Following are the clinical indications for performing the Tau/Aß42 Cerebrospinal Fluid Test:

  • Memory loss
  • Personality changes
  • Impaired mental ability
  • Hallucinations
  • Impulsive behavior 

How is the Specimen Collected for Tau/Aß42 Cerebrospinal Fluid Test?

Following is the specimen collection process for Tau/Aß42 Cerebrospinal Fluid Test:

Sample required: Cerebrospinal fluid

Process: Insertion of a needle into the spine.

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the Tau/Aß42 Cerebrospinal Fluid Test Result?

  • Increased levels of tau and decreased levels of Aß42 may indicate Alzheimer’s disease 

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario. 

Additional and Relevant Useful Information:

  • Certain factors may interfere with the results of this Tau/Aß42 CSF Test. These include AIDS and cerebrovascular diseases
  • It is possible for an individual with Alzheimer’s disease to display normal levels of tau protein, because of an insufficient number of brain tangles. This may result in a false negative test result 

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: July 17, 2014
Last updated: Sept. 14, 2018