Alzheimer's Disease: Blood Test

The first blood test to detect the presence of amyloid, a hallmark of Alzheimer's disease (AD), is now available for clinical use, the company behind the test's development, C2N Diagnostics, has announced. The availability of the noninvasive, easily administered test is being called a milestone in the early detection and diagnosis of AD.

The test is not FDA approved and it does not, on its own, diagnose Alzheimer's.

The test has only been studied in a limited number of individuals and that few data are available regarding underrepresented populations.

The test (PrecivityAD) is for use in patients with cognitive impairment. It requires a very small blood sample ― as little as a teaspoon ― from the patient's forearm. The physician sends the sample to C2N Diagnostic's specialized laboratory, where it's analyzed using mass spectrometry to measure concentrations of amyloid beta 42 and 40 and to detect the presence of apolipoprotein E isoforms.

The lab report, which is sent to the patient's physician, details biomarker levels and provides an overall combined score, known as the Amyloid Probability Score, to assess the likelihood of low, intermediate, or high levels of amyloid plaque in the brain.

The company reports that, on the basis of data from 686 patients older than 60 years who had subjective cognitive impairment or dementia, the test correctly identified brain amyloid plaque status, as determined by quantitative amyloid positron-emission tomography (PET) scans, in 86% of the patients. In the analysis, the area under the curve for the receiver operating characteristic was 0.88.

The company notes that the test, the results of which require interpretation by a healthcare provider, is an important new tool to aid physicians in the evaluation process.

The new blood test is not currently available in Europe.