Contributed Commentary by Ashton Harper, Roche Diagnostics
January 9, 2026 | There can be little debate that Alzheimer’s disease is one of the greatest healthcare challenges we face globally. Most recent estimates suggest that over 57 million people worldwide are living with dementia, of which 70% is caused by Alzheimer’s. With aging societies, this number is expected to increase to over 150 million by 2050.
Anybody who has had a personal experience with this disease will know just how devastating it can be, with the power to take the very essence of who we, or our loved ones, are. In fact, a recent study in the UK found that dementia has overtaken cancer as people’s perceived biggest threat to their health.
Yet there is a growing sense of impending change, particularly because the way we diagnose Alzheimer’s is now at a pivotal moment. Advances in technology, particularly in blood-based biomarkers (BBBMs), are opening up new possibilities for simpler, faster, and more accessible diagnostic solutions. This progress could revolutionize the way Alzheimer’s disease is identified and managed, ushering in a new era of hope for patients and caregivers alike.
Diagnosing Alzheimer’s Disease is Critical
It is estimated that as many as 75% of people with dementia have never received a diagnosis, and those who have wait three and a half years on average to get one. Yet, with everything we now know about the etiology of Alzheimer’s disease and the latest understanding of lifestyle interventions and treatment options available, it’s clear that people who experience distressing symptoms of cognitive decline deserve swift answers.
Firstly, cognitive symptoms may not necessarily be caused by Alzheimer’s disease, and so, ruling it out is a critical step in ensuring clinicians can explore other possible causes and interventions. Confirmation of an Alzheimer’s diagnosis can help people plan for their future and access vital support they may need.
An early diagnosis empowers people to make simple changes to their diet and exercise levels, which a growing body of evidence suggests could have a significant impact on their disease outcomes.
Finally, timely diagnosis enhances treatment access—from medicines that may help to manage symptoms to emerging disease-modifying therapies (DMTs) that slow down or even prevent its progression. DMTs target the underlying biology and are most effective when used earlier in the course of the disease. It also means more patients can enroll in clinical trials to further improve our understanding of Alzheimer’s and unlock the next generation of treatments.
Gold Standard Comes at a Cost
The gold standard in Alzheimer’s diagnosis is positron emission tomography (PET) scanning. This imaging test can detect amyloid pathology in the brain and is approved by various regulatory agencies around the world. Yet, its widespread use is restricted by high costs and the need for complex infrastructure. Although the dose is low and short-lived, PET scans also require a radioactive tracer to be injected.
There is a pressing need for alternatives that offer cheaper, faster, and more accessible options for people and healthcare systems globally.
Biomarkers are the Benchmark for Accessible Solutions
Biomarkers are molecular indicators found in blood, tissue, or other body fluids that can be a sign of both normal and abnormal processes. Unlike medical symptoms, which are reported subjectively by patients, biomarkers are measurable and reproducible, providing an objective assessment of changes in the body.
In Alzheimer’s disease, biomarkers including amyloid-beta (Aβ) and phosphorylated tau (pTau) can enter the bloodstream—possibly because the blood-brain barrier becomes ‘leaky’. Their presence in the blood and other body fluids offers the potential for them to be measured and provide an indication of the disease state. There are several potential biomarkers of interest in Alzheimer’s disease.
CSF Testing Shows Parity in Performance
Biomarkers of Alzheimer’s disease can also be detected in cerebrospinal fluid (CSF) and, therefore, provide an indication of disease activity. In vitro diagnostic (IVD) tests can identify these biomarkers in CSF and are the first to show high concordance with PET imaging, presenting a highly accurate alternative. CSF tests are potentially cheaper, more accessible, and scalable than PET scans, with demand for CSF testing to diagnose Alzheimer’s expected to rise.
Beyond diagnosis, more affordable and accurate CSF testing could provide additional information in the Alzheimer’s disease patient pathway, including disease severity and staging, progression risk, response to therapies, patient stratification, and efficacy of treatments in clinical trials.
Yet barriers remain in CSF testing, primarily around the invasive nature of sample collection, which involves a lumbar puncture or “spinal tap”. This is a medical procedure where a needle is inserted into the lower back, which some may be reluctant to undergo.
The latest innovations have resulted in tests coming to market that can detect Aβ or pTau proteins at very low concentrations in the blood. The reality of this is that a simple blood test could aid in the diagnosis of Alzheimer’s disease, providing a more cost-effective, accessible, and scalable solution that is also less invasive than PET scans or CSF IVDs.
It’s important to note that BBBMs are indicative of amyloid pathology, rather than Alzheimer’s disease itself. For now, this means they should be used in conjunction with other clinical information, such as symptom presentation and PET scans, to confirm a diagnosis of Alzheimer’s disease. What they offer is a simpler, less invasive way of detecting these hallmark pathological proteins. This can help to triage people who present with neurological symptoms by ruling out those who do not have amyloid pathology and ruling in those who do have amyloid pathology and may benefit from further diagnostic testing. As BBBM tools develop, there is a hope that their utility may advance from triage to confirmation of disease, comparable to the current gold standard.
With more BBBMs becoming validated for use in clinical practice, it is essential that they are evaluated in diverse patient populations reflective of real-world clinical practice. They need to be robust and stable under storage conditions for use in various settings and provide opportunities to support diagnostics across the patient pathway, for example, in both primary and secondary care.
Diagnosing Pre-Symptoms for the Biggest Impact
New BBBM tests in development could help identify people who carry the APOE4 gene variant, which increases the risk of developing Alzheimer’s disease. While genetic testing can identify the presence of the APOE4 variant, these tests are often expensive and inaccessible to many. BBBM tests, alongside other diagnostic tools, could provide a more accessible alternative and support the early identification of those at risk. This early insight could help ensure individuals receive the best care possible—even before symptoms appear—potentially slowing disease progression.
Towards the Ultimate Goal
The ultimate goal for Alzheimer’s disease is to slow down or stop progression in symptomatic disease and, in the future, hopefully prevent Alzheimer’s dementia altogether. None of that is possible without a diagnosis. Through advances in diagnostic testing—primarily our understanding of BBBMs—we are better placed than ever to get people the cost-effective, accurate, and timely answers they need. That’s true innovation.
Ashton Harper is the Global Medical Affairs Indication Lead for Neurosciences at Roche Diagnostics, providing strategic direction for Roche Diagnostics' rapidly growing neurology portfolio, focusing on evidence generation, external collaborations, medical education, and KOL engagement. Ashton joined Roche Diagnostics in August 2020 as the Head of Medical Affairs for the UK & Ireland, leading clinical research across various therapeutic areas, including oncology, cardiology, neurology, infectious diseases, critical care, and women’s health. Ashton studied medicine at University College London, earning both an MBBS and a B.Sc. in physiology and pharmacology. He worked as a doctor in the NHS and achieved membership in the Royal College of Surgeons. During his surgical training, he was awarded a postgraduate fellowship to the Cleveland Clinic in the USA to observe experts in inflammatory bowel disease. He can be reached out at ashton.harper@roche.com.