Highly accurate blood test for Alzheimer’s disease diagnosis

The availability of a blood test to detect Alzheimer’s disease before the first symptoms arise is moving closer towards reality. Beginning of August 2019, US researchers from the Washington School of Medicine reported highly encouraging results. In their paper, published in the peer-reviewed journal of Neurology, the authors stated they were able to accurately assess, prior to the onset of cognitive symptoms, blood levels of amyloid beta protein, the causative agent of Alzheimer’s disease.

These authors performed a cohort study involving 158 adults, over 50 years of age. All participants were cognitively normal with the exception of 10. Each participant provided at least one blood sample and underwent a positron emission tomography (PET). So far, the PET brain scan has been considered the gold standard to detect the beginnings of amyloid deposition in the brain.

Both the subjects’ blood sample and PET scan were classified as amyloid positive or amyloid negative. In 88% of cases, the blood test results positively correlated with those obtained by PET scanning. Though clearly promising, this 88% accuracy figure may not suffice for a diagnostic tool in clinical practice. When combining the blood test outcome with two other major risk factors for the disease, age and the genetic variant APOE4, the test’s accuracy improved reaching 94%.

Of note, this simple blood test may actually prove more sensitive that the current reference tool: PET scanning. This latter is expensive, time-consuming, and hardly applicable on a large scale. Further studies are required to confirm these positive yet still preliminary results.

https://www.ncbi.nlm.nih.gov/pubmed/31371569

Reference: Schindler SE, Bollinger JG, Ovod V, Mawuenyega KG, Li Y, Gordon BA, Holtzman DM, Morris JC, Benzinger TLS, Xiong C, Fagan AM, Bateman RJ. High-precision plasma β-amyloid 42/40 predicts current and future brain amyloidosis. Alzheimers Dement. 2019 Aug 1. pii: S1552- 5260(19)30122-0. doi: 10.1016/j.jalz.2019.04.015. [Epub ahead of print]