Description
A blood-based biomarker test that may help assess the likelihood of amyloid plaque accumulation associated with Alzheimer’s disease.
The Beta Amyloid 42/40 Ratio, Plasma by Labcorp test measures two forms of beta-amyloid protein—Aβ42 and Aβ40—and calculates their ratio. Changes in this ratio may reflect amyloid accumulation in the brain, one of the hallmark biological features associated with Alzheimer’s disease.
What Does This Test Measure?
The test measures:
- Beta Amyloid 42 (Aβ42)
- Beta Amyloid 40 (Aβ40)
- Aβ42/Aβ40 Ratio
A lower Aβ42/40 ratio is generally associated with a greater likelihood of cerebral amyloid deposition.
Who May Consider This Test?
This test may be useful for adults experiencing or being evaluated for:
- Memory loss
- Mild cognitive impairment
- Progressive cognitive changes
- Concerns about Alzheimer’s disease
- A family history of Alzheimer’s disease or dementia
- Further evaluation of cognitive symptoms
Why Test Beta Amyloid?
Amyloid changes can begin years before significant cognitive symptoms develop. Blood-based biomarkers provide a convenient way to evaluate Alzheimer-related biological changes without initially requiring more invasive cerebrospinal fluid testing.
Results should be interpreted together with the individual's symptoms, medical history, cognitive evaluation, and other appropriate testing.
Important Limitations
The Beta Amyloid 42/40 Ratio is not a stand-alone diagnosis of Alzheimer’s disease. An abnormal result does not by itself establish that a person has Alzheimer’s disease, and a normal result does not exclude all causes of cognitive impairment or dementia.
Additional evaluation may include other Alzheimer biomarkers such as p-tau217 or p-tau181, neurological evaluation, cognitive testing, and brain imaging when appropriate.
Specimen: Plasma Test Type: Blood test Preparation: No special preparation typically required
