What is the new Alzheimer’s blood test?
- Researchers have developed a new blood test to detect Alzheimer’s disease that helps diagnose the disease even at the early stage of mild cognitive impairment.
- Scientists at Lund University in Sweden have shown that PrecivityAD2, a new blood test, is about 90% accurate in identifying AD in people experiencing cognitive symptoms.
Key Highlights
- According to statistics, one in five women and one in 10 men develop dementia due to AD (Alzheimer’s disease).
- Individuals with cognitive symptoms are first seen in primary care, with a minority being referred to secondary care, authors of the article pointed out.
- Further they added that symptomatic AD is misdiagnosed in 25% to 35% of patients treated at even specialised clinics and likely even more patients treated in primary care.
- For long, a blood test has been the Holy Grail for diagnosis of AD, since even current, modern methods of diagnosis involve very expensive and complex amyloid or Tau Positron Emission Tomography (PET) scans.
- The other alternative is to draw cerebrospinal fluid via a painful procedure, lumbar puncture.
- This blood test comes as close to the target as possible, and in that sense will make the diagnosis of AD very simple.
- Blood tests will not only reduce the costs of diagnosis, but also simplify the diagnostic procedure involving, as it does, just drawing of blood.
- There have been a few commercial attempts that went live before this test, but the current study has provided some definitive results.
What does the test do?
- According to Medical News Today, the test works by measuring a combination of two ratios within a blood sample: plasma phosphorylated-tau217 (also called p-tau217) to not-phosphorylated-tau21 and two types of amyloid-beta: AB42 and AB40.
- Let it suffice for us to understand that both tau and amyloid-beta proteins are currently considered pathological hallmarks of AD.
- A total of 1,213 patients were already under evaluation for cognitive decline in primary or secondary care centres between February 2020 and January 2024 in Sweden.
- Of the participants, 23% had subjective cognitive decline, 33% had dementia, and 44% had mild cognitive impairment.
- About 50% of participants showed Alzheimer disease pathology through primary and secondary care testing.
- In comparison to the blood test that had an accuracy of 91%, dementia specialists identified clinical Alzheimer disease with a diagnostic accuracy of 73%, the researchers say in their paper.
- In primary care, physicians had a diagnostic accuracy of 61%.
- They argue that this would be an accurate blood test for AD and that it could streamline the diagnostic workup and treatment of AD.
- The significance is that there are several drugs that work in the early stages of the disease, and an early, cost-effective, simple diagnosis will go a long way for patients, experts say.
Way forward
- Future studies should evaluate how the use of blood tests for these biomarkers influences clinical care, researchers have said in their paper.
- No doubt the costs will come down, naturally impacting positively on affordability.
- Availability is the other issue.