What is Alzheimer’s Disease?
New Alzheimer’s Blood Tests can predict early the most common form of dementia.
It is a progressive, degenerative brain disorder that causes gradual loss of memory, thinking skills, behavior changes, and the ability to perform daily activities. In Alzheimer’s disease, two main abnormal proteins build up in the brain:
- Beta-amyloid (Aβ): forms plaques around nerve cells.
- Tau protein: when hyperphosphorylated (pTau), it forms intracellular neurofibrillary tangles.
These changes lead to loss of connections between neurons, inflammation, and eventually neuron death.
Alzheimer’s Disease Biomarkers
To date, positron emission tomography (PET) and cerebrospinal fluid (CSF) biomarkers where used to detect Aβ and Tau pathologies, but new blood-based biomarkers are increasingly preferred to detect Alzheimer’s pathology with high accuracy, even in early stages, because they are more easily accessible, minimally invasive and cost-effective.
Main blood biomarkers for Alzheimer’s Test:
- p-Tau-217 (phosphorylated tau protein 217)
- p-Tau-181 (phosphorylated tau protein 181)
- Aβ1-42 (β-amyloid 1-42)
- Aβ1-40 (β-amyloid 1-40)
pTau-217 : The most reliable single blood biomarker for Alzheimer’s. Elevated levels indicate accumulation of amyloid plaques and neurofibrillary Tau tangles.
pTau-181: Elevated levels indicates neurofibrillary Tau tangles.
Aβ1-42/Aβ1-40 ratio: Decreased levels indicate accumulation of amyloid plaques.
p-Tau-217/Aβ1-42 ratio. Elevated levels indicate accumulation of amyloid plaques and neurofibrillary Tau tangles. It is the most reliable blood biomarker for Alzheimer’s.
Profiles with low Aβ1-42/Aβ1-40 ratio, high p-Tau-181, high p-Tau-217 and high p-Tau-217/Aβ1-42 ratio indicate the presence of Alzheimer’s disease pathology with high accuracy.
Who is the Alzheimer’s Disease Biomarker test for?
Who is the Alzheimer’s blood biomarker test for?
- Adults with cognitive symptoms, especially those aged 50-55 years and older.
- People experiencing objective cognitive impairment, such as:
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- Memory loss that interferes with daily life.
- Difficulty with thinking, planning, or problem-solving.
- Confusion, language problems, or changes in behavior.
- Mild Cognitive Impairment or suspected early dementia.
- Individuals being assessed for Alzheimer’s disease and other causes of cognitive decline.
How soon can biomarkers from the Alzheimer’s blood test predict onset of disease?
Early accumulation of amyloid on PET scans begins approximately 10-20 years prior to the average age of symptom onset, pTau217 can be detected years earlier, even when initial brain scans appear normal.
Notably, the time from when elevated pTau217 first appeared to the onset of Alzheimer’s symptoms got shorter as people aged. A person with elevated ptau217 at age 60 would develop symptoms about 20 years later. Meanwhile, a person whose pTau217 became elevated at age 80 would develop symptoms after only 11 years.
Although less sensitive compared to pTau217, plasma pTau181 accurately predicts Alzheimer’s disease pathology aτ 8-16 years prior to symptom onset and improves the clinical characterisation of cognitive decline.
Aβ42/Aβ40 ratio is sensitive to very early amyloid accumulation (becomes abnormal on average approximately 2 years before amyloid plaques are detected by PET), but is less specific alone compared to pTau markers.
What are the benefits of Alzheimer's biomarker tests?
- Enable early and accurate diagnosis.
- Help rule out other causes of dementia.
- Support clinical decisions for starting new disease-modifying treatments.
Biomarkers should always be interpreted by a healthcare professional in conjunction with clinical and cognitive assessment.
StArtBio Test Offers
Alzheimer's Disease 4 Biomarkers Test €250 (click here to see what is included)
p-Tau-217 (phosphorylated tau protein 217)
p-Tau-181 (phosphorylated tau protein 181)
Aβ1-42 (β-amyloid 1-42)
Aβ1-40 (β-amyloid 1-40)