The Alzheimer’s Association has released new clinical guidelines recommending the use of blood tests to help diagnose patients with cognitive impairment, potentially leading to more people receiving treatment for the disease. The guidelines suggest that blood tests with over 90% sensitivity and specificity can be used in place of more complex and invasive methods like PET scans and cerebrospinal fluid tests.
These tests could be used to triage patients, ruling out Alzheimer’s with high probability for negative results, while positive results should be confirmed with standard diagnostic methods due to the possibility of false positives. The guidelines emphasize that they are not a substitute for a full clinical evaluation and apply only to patients under the care of specialists who have already been confirmed to have cognitive impairment.
While the guidelines do not endorse specific tests, they reviewed several that measure biomarkers like pTau217 and Aβ42 to Aβ40 ratios. The Alzheimer’s Association plans to provide an online portal with a chart of the various tests and their accuracy, which will be continually updated. The approval of new Alzheimer’s drugs has led to a push for blood tests as a more convenient and cost-effective diagnostic tool, with one test already approved by the FDA.
The recommendations are expected to be updated over time, potentially leading to more patients getting tested and diagnosed, especially in rural areas where access to scans and spinal fluid tests is limited. While blood tests can detect the presence of amyloid in the brain, they are not reliable for measuring the amount of amyloid present, which is crucial for monitoring patients receiving treatment.
The guidelines also serve as a call to action for researchers to conduct studies and publish results that provide strong evidence for the accuracy of blood tests in diagnosing Alzheimer’s. The Alzheimer’s Association aims to ensure that only tests with robust evidence are recommended for clinical use.
