Scientists at CSIRO, Australia's national science agency, have identified simpler and less invasive methods to improve Alzheimer's disease diagnosis, potentially making it easier for patients to access emerging treatments.
New treatments like Donanemab, recently approved by the Therapeutic Goods Administration (TGA) for adults with early symptomatic Alzheimer's, require confirmation of amyloid plaque in the brain.
Currently, the gold standard for detecting amyloid plaque involves costly PET scans or and invasive lumbar punctures to analyse cerebrospinal fluid.
In a new study published in Alzheimer's and Dementia, scientists found that combining two blood tests – the Lumipulse plasma pTau217 test and the Aβ42/40 ratio test – could match the accuracy of the existing 'gold standard' methods.
Dr James Doecke, lead author on the paper and Research Scientist at CSIRO's Australian e-Health Research Centre (AEHRC), said blood tests are vital to the triage process to develop appropriate treatment strategies and help understand where a person is on the disease trajectory.
"With treatments for Alzheimer's disease biology becoming available, it's critical we have accurate, scalable and less invasive tests to identify eligible patients," Dr. Doecke said.
"Our findings show this blood test combination performs at the level needed to confirm Alzheimer's pathology."
CSIRO's AEHRC, in partnership with Edith Cowan University, The Florey Institute, Labcorp and others, analysed blood samples from nearly 400 participants.
The samples were sourced from the Australian Imaging, Biomarker and Lifestyle (AIBL) Study of Ageing in two groups:
- An Alzheimer's Disease Continuum cohort, spanning cognitively healthy individuals through to those with Alzheimer's disease
- An Intention-to-Treat cohort, representing patients who would be eligible for new disease-modifying therapies such as Donanemab.
Results showed that the combined pTau217/Aβ42 ratio achieved over 93 per cent accuracy, similar to the current gold-standard cerebrospinal fluid tests.
In the Intention-to-Treat cohort, sensitivity reached 99 per cent, meaning the tests correctly identified nearly all cases.
Using the tests combined provided clinicians with highly reliable results, reducing the number of uncertain cases by nearly half.
"This is an important advance towards widespread adoption of blood tests in both clinical trials and everyday practice," said co-author, Colin Masters, Professor of Dementia Research at The Florey Institute.
The study highlights the potential for blood-based biomarkers to reduce reliance on costly and invasive PET scans and lumbar punctures, making diagnosis more accessible to patients and healthcare systems worldwide.
