What’s tested

Blood-biomarker tests for early detection may include those associated with the peptide amyloid-β (also known as A-beta). The AD-Detect Test for Alzheimer’s Disease measures two peptide amyloid- βs: A-beta 42 and A-beta 40, and provides the A-beta 42/40 blood levels ratio.

Amyloid beta proteins are known to accumulate and form plaques in the brain, which are linked to the progression of Alzheimer's disease. A-beta 42 and A-beta 40 are biomarkers that are produced when the protein amyloid precursor protein (APP) is broken down. A-beta 42 is a longer fragment of APP, while A-beta 40 is a shorter one. The A-beta 42/A-beta 40 ratio is a measure used in AD research to indicate the presence of amyloid beta proteins in the brain. The A-beta 42/A-beta 40 ratio is important because A-beta 42 is known to be likely to clump and form plaques, making it less detectable. A-beta 40 is more soluble and less likely to form plaques. Because of this, a lower ratio of A-beta 42 to A-beta 40 in the brain is associated with a greater risk of developing Alzheimer's disease.

Prior to blood-biomarker testing, neurologists could only rely on cognitive assessment and brain imaging to diagnose Alzheimer’s. Unfortunately, these methods made identifying Alzheimer’s disease from other forms of dementia difficult. This test helps differentiate Alzheimer’s from other forms of dementia as the likely, underlying cause of a person’s mild mental impairment.