Australian researchers say a two-marker blood test could help confirm Alzheimer’s faster, at lower cost, and with less burden on patients and clinics. The approach pairs plasma pTau217 with the Aβ42 to Aβ40 ratio to flag amyloid pathology, the same target doctors must confirm before prescribing new disease-modifying drugs. Early validation work in Australian cohorts shows high agreement with current gold standards. That means fewer spinal taps and fewer PET scans for many patients, while still giving clinicians confidence to act. (The Lancet)
The timing matters. Australia’s regulator has approved donanemab for people with early symptomatic Alzheimer’s, but access depends on confirming amyloid in the brain and on careful risk screening. PET scans and lumbar punctures are accurate, yet they are costly, invasive, and hard to scale. A reliable blood route could widen the front door to treatment by helping triage who needs advanced imaging and who can proceed sooner. It could also shorten wait lists and reduce out-of-pocket costs tied to multiple visits and scans. (InSight+)
What The New Blood Test Approach Does
Researchers at CSIRO’s Australian e-Health Research Centre and partners including The Florey Institute, Edith Cowan University, and Labcorp evaluated pTau217 measured on widely available lab platforms and combined it with a blood Aβ42 to Aβ40 ratio. Studies in Australian cohorts such as AIBL show pTau217 strongly tracks brain amyloid and tau measured by PET and CSF. When used together, these blood markers can reach over 90 percent accuracy for detecting biological Alzheimer’s disease in real-world settings. That level of performance is useful for triage and for confirming pathology in many routine cases. (The Lancet)
Crucially, laboratories are moving the technology into clinical workflows. Fujirebio’s Lumipulse pTau217 to Aβ42 plasma ratio is the first FDA-cleared blood test to aid Alzheimer’s diagnosis in symptomatic adults. US availability accelerates method standardisation and quality controls, which helps global adoption and supports Australian validation studies. Local clinical programs led by the Australian Dementia Network are also training GPs to use blood biomarkers appropriately in primary care. (neurologylive.com)
How This Could Change Care Pathways
- Start with a simple blood draw in primary or specialist care when a person presents with mild cognitive impairment or early dementia symptoms.
- Use validated plasma pTau217 and Aβ42 to Aβ40 tests to assess likelihood of Alzheimer’s pathology.
- Fast-track eligible patients to amyloid-targeting therapy workup, including MRI safety checks and, when needed, confirmatory PET or CSF.
- Reserve PET and lumbar puncture for cases where blood results are borderline, discordant with the clinical picture, or where other neurodegenerative conditions are suspected.
- Monitor disease with a mix of cognitive tools and targeted imaging, using blood biomarkers for follow up when appropriate. (Healthed)
Why It Matters For Australian Patients Right Now
Australia now permits donanemab for early Alzheimer’s, but how many people benefit depends on fast and fair diagnosis. PET scanners are unevenly distributed, travel can be long, and wait lists are growing. Blood tests can be run on high-throughput analysers already sitting in hospital labs, which lowers barriers for regional and outer-metro communities. A triage-first model can also cut time to a yes or no for therapy. That means fewer missed windows where intervention is most effective. (ABC)
Cost is another lever. Media reports and expert commentary place total treatment pathways in the tens of thousands of dollars before any subsidy, with separate costs for drug, imaging, and safety monitoring. If blood tests reduce the number of PET scans and streamline clinic visits, the overall bill drops for patients and the system. Subsidy decisions through the Pharmaceutical Benefits Scheme will still determine affordability. Until then, a scaled blood pathway can prevent unnecessary big-ticket imaging for people who are unlikely to be eligible. (The Guardian)
H3: Comparing Alzheimer’s Diagnostic Pathways In 2025
| Pathway | What it measures | Setting and availability | Typical role | Pros | Considerations |
|---|---|---|---|---|---|
| Plasma pTau217 plus Aβ42 to Aβ40 | Blood markers linked to amyloid and tau pathology | Hospital and reference labs using automated platforms | First-line triage and, in many cases, confirmation to proceed | Low burden, scalable, fast turnaround | Borderline results may still need confirmatory imaging (Healthed) |
| Amyloid PET scan | Fibrillar amyloid in brain | Tertiary centers with PET access | Confirmatory test and therapy eligibility | High diagnostic accuracy, visual evidence | Expensive, limited access, radiation exposure, wait lists (The Guardian) |
| CSF Aβ and tau via lumbar puncture | Core Alzheimer’s proteins in CSF | Specialist centers | Gold-standard confirmation | High accuracy, widely accepted | Invasive, requires skilled staff and patient consent (Healthed) |
| FDA-cleared Lumipulse plasma ratio | pTau217 to Aβ42 plasma ratio | Commercial launch in the US, spreading to more labs | Diagnostic aid for symptomatic adults | Standardised assay, quality system, supports scale | Regulatory and reimbursement pathways vary by country (neurologylive.com) |
H4: Practical Steps For Clinicians And Health Services
Clinicians should map a local workflow that starts with validated blood biomarkers for patients who have cognitive complaints or mild impairment. Build clear thresholds for moving to confirmatory PET or CSF only when needed. Align with emerging guidance from specialty societies and Australian Dementia Network training to ensure consistent test ordering, interpretation, and patient communication. Track turnaround times and false positive follow-ups to fine-tune your thresholds over time. (Healthed)
Health services can prepare by checking whether their partnered pathology providers offer pTau217 and Aβ42 to Aβ40 assays on automated platforms. Where not yet available, document the current PET and CSF capacity and model how much capacity could be freed by a blood-first pathway. Use those estimates to plan staffing, booking systems, and equity measures for rural and remote patients who face longer travel for scans. As PBS decisions on donanemab evolve, be ready to update referral criteria and shared decision aids. (The Lancet)
Trending FAQ
What exactly is being measured in the blood tests?
They measure phosphorylated tau at residue 217 and the ratio of amyloid beta 42 to amyloid beta 40. Both relate to amyloid and tau changes that define Alzheimer’s biology. (Healthed)
Are the blood tests as accurate as PET or CSF?
Large studies show pTau217 and the Aβ42 to Aβ40 ratio can exceed 90 percent accuracy for detecting Alzheimer’s pathology, with strong correlation to PET and CSF. Borderline or conflicting results still need confirmatory testing. (Healthed)
Is the test available in Australia today?
Australian labs are validating assays on automated platforms used in routine pathology, and clinicians are being trained through national programs. The first FDA-cleared plasma test is already on the market in the United States, which supports global implementation. Check local labs for availability. (Healthed)
Why is this linked to treatment access?
Donanemab requires early diagnosis and confirmation of amyloid pathology. A reliable blood test can identify who should progress to therapy workup faster, and who should avoid unnecessary scans. (ABC)
How much will the full pathway cost patients?
Prices vary. Reports suggest high out-of-pocket costs for drug and imaging before any subsidy. A blood-first pathway can reduce the number of PET scans and visits, which may lower overall costs while PBS decisions are pending. (The Guardian)
What should primary care do now?
Use structured cognitive assessments, refer for blood biomarkers when available, and escalate to specialists for complex or discordant cases. National training resources are in place to support safe adoption. (Healthed)
How does this help rural and regional communities?
Blood tests run on high-throughput machines are easier to distribute than PET capacity. That can shorten waits and travel for many patients outside major cities. PET and CSF remain important when blood results are unclear. (The Lancet)
Do these tests screen healthy people?
No. They are intended for adults with symptoms consistent with mild cognitive impairment or early dementia, to help determine if Alzheimer’s biology is present. (neurologylive.com)
What comes next in 2025 and 2026?
Expect more labs to stand up validated assays, more guidance on thresholds, and clearer links between blood results and therapy eligibility and safety monitoring. As evidence grows, triage protocols will keep improving for speed, equity, and cost. (The Lancet)
