How is it used?When is it ordered?What does the test result mean?Is there anything else I should know?
Tests for Tau protein and Aß42 may be used as supplemental tests to help establish a diagnosis of
Alzheimer's Disease.
If a patient has symptoms of dementia, such as memory loss, behavioral changes, and decreased ability to perform daily life functions, the doctor will do a thorough work-up to try to determine the cause. This work-up may include a variety of cognitive tests to assess memory and possibly scanning tests of the brain to look for abnormalities.
Tau protein and Aß42 are not currently part of a typical assessment of a patient. However, abnormal levels of these two proteins in CSF may help distinguish AD from other forms of dementia.
Currently, Tau protein and Aß42 tests primarily are performed in research settings, in conjunction with cognitive tests and brain scans. Some doctors may order them outside of research settings; however, information on how to interpret the results is limited.
What does the test result mean?NOTE: This test has no single number that identifies an abnormal result.
Your lab report (see a sample report) should include
a range of numbers (reference range) that identifies what is expected for you based on
your age, sex, and the method used in that laboratory. You can find more information
about expected results at Reference Ranges
and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.
In a symptomatic patient, low Aß42 along with high Tau reflects an increased likelihood of
Alzheimer’s Disease, but it does not mean that the person definitely has AD. If a patient does not have abnormal levels of these proteins, then the dementia is more likely due to a cause other than AD.
Is there anything else I should know?
Assessments of Aß42 and Tau protein levels do not establish a diagnosis of Alzheimer’s Disease; they represent a common finding that may be used in conjunction with other tests and the patient’s clinical and family history to suggest a diagnosis of AD.
In AD patients, the findings of low Aß42 levels and high Tau protein levels appear to be unrelated to the cause or the age of onset of Alzheimer’s Disease.
