Transforming Early Symptomatic Alzheimer’s Disease Diagnostics: The Emerging Role and Potential Impact of Blood Biomarker Testing in Early Detection

A Critical Need for Early Intervention in Early Symptomatic Alzheimer’s Disease

Alzheimer’s disease is a debilitating neurodegenerative disorder affecting nearly 7 million Americans over the age of 65 – a number expected to double to almost 14 million by 2060.¹

Despite growing disease awareness, a significant portion of adults with symptoms remain undiagnosed, particularly those in the stages of disease when symptoms are milder and often mistaken for normal aging.¹ This delay can mean the difference between early intervention and irreversible decline. Timely detection and diagnosis of early symptomatic Alzheimer’s disease are crucial as they enable earlier initiation of informed disease management, earlier opportunities to support cognitive well-being, and earlier consideration of potential treatment options.

Now, a promising innovation is changing what’s possible: blood biomarker testing. By allowing for more accessible and less invasive detection of early symptomatic Alzheimer’s disease pathology, this new tool can help patients who meet testing criteria be diagnosed earlier in the symptomatic disease and be able to make informed care decisions with their physician.

The Lengthy Road to Diagnosis – and Why it Still Takes Too Long

In recent years, tools like amyloid PET imaging and cerebrospinal fluid (CSF) analysis have advanced diagnostic capabilities beyond post-mortem confirmation. While these methods remain important and may be necessary for confirmatory diagnosis or treatment eligibility in some cases, new advances like blood biomarker testing have the potential to streamline the diagnostic process.^2,3 By helping to triage and identify patients who may benefit from further evaluation, blood diagnostics can enable smarter, more efficient use of all available tools, including PET and CSF, supporting accurate and timely diagnosis across a range of clinical settings.^2,3

“Blood biomarker tests are certainly more accessible and less invasive,” said Michelle Mielke, PhD, Professor of Epidemiology, Gerontology & Geriatric Medicine, Wake Forest University School of Medicine. “They help expand diagnostic access, particularly for people in rural and underserved areas, and can help guide decisions about when to use more specialized tests.”

Additionally, many healthcare providers may have limited awareness of the emerging blood diagnostic tools or may be hesitant to adopt them due to uncertainties around their utility, reliability, or interpretation. This knowledge gap underscores a need for continued education and clear guidance for healthcare professionals to effectively incorporate blood diagnostics into Alzheimer’s care.

What ultimately delays diagnosis is that early signs of early symptomatic Alzheimer’s disease are often mistaken for normal aging or are ignored due to fear or stigma, leading to underreporting and delayed evaluation. Patients and their families frequently don’t seek help until symptoms have progressed, causing missed opportunities for earlier interventions, including lifestyle modifications and potential treatment options.⁴

A New Era of Early Detection: The Promise of Blood Biomarker Tests

Blood biomarker tests provide valuable insights into a patient's health status and disease. They also represent a transformative leap in diagnostics for early symptomatic Alzheimer’s disease. These tests detect amyloid beta and phosphorylated tau proteins – the hallmark pathologies of the disease – through a simple blood draw.

“Blood biomarkers are opening doors for broader screening and earlier identification of Alzheimer’s disease, especially for patients who previously lacked access to more specialized testing,” said Mielke. Some blood biomarker tests have shown strong correlation–up to 90% accuracy–with amyloid PET scans, such that they could be a scalable option for aiding in the assessment of amyloid pathology.^5,6

As Mielke explained, these tests, along with clinical assessment results, could help clinicians triage patients before ordering PET scans or CSF tests. “If a blood biomarker comes back negative, maybe you don’t go on to CSF or PET testing,” said Mielke. “If it comes back positive, that can guide the next steps.”

Realigning the Diagnostic Pathway

The potential utility of blood biomarkers goes beyond neurology clinics. Cognitive complaints are often first raised in primary care, yet physicians in these settings face time constraints, confusion on what tests to order, and less familiarity with available diagnostic tools.

“In primary care, you might be dealing with a 15-minute visit and six chronic conditions,” said Mielke. Blood biomarkers offer a way to assess and stratify patients with cognitive impairment more efficiently by identifying whether they have amyloid pathology. This can potentially enable earlier specialist referrals or help rule out early symptomatic Alzheimer’s disease in patients with other causes of cognitive decline. Still, communication between primary care providers and neurologists must improve to ensure continuity of care.

“We’ve heard of primary care providers ordering blood biomarker tests, getting a positive result, and not necessarily having clear guidance of what to do next,” Mielke noted. “It’s really important we establish clear pathways and better coordination.”

Diagnostic Clarity, Emotional Relief

For families living in uncertainty, a timely and accurate diagnosis can bring both clarity and peace of mind. But patient preference varies and must be respected.

“Some patients want to know everything. Others don’t want to know anything,” Mielke reflected. “It’s important to understand what patients and families want before testing and to explain both the utility and the limitations of the results.”

Even a positive biomarker result along with a cognitive assessment doesn’t guarantee that early symptomatic Alzheimer’s disease is the only cause of a given patient’s cognitive decline. Mixed pathologies, including vascular, Lewy body, and TDP-43, are common in older adults. Blood tests should be used in context, not in isolation, to help identify amyloid pathology.

Opening the Door to More Comprehensive Early Symptomatic Alzheimer's Disease Management & Planning for the Future

Timely and accurate diagnosis can prompt changes that support cognitive well-being and help patients make informed decisions about next steps with their doctors and their loved ones. With more time to plan, individuals can also express their preferences regarding medical care, living arrangements, and legal and financial matters – helping to ensure their wishes are respected as the disease progresses.

That’s why timely diagnosis is critical. And blood biomarkers could help make that possible for more patients.

Looking Ahead to Precision Neurology and Equitable Access

As researchers work to develop biomarkers for additional neurodegenerative pathologies, the long-term vision is precision neurology: individualized diagnosis and care informed by a patient’s unique biological profile.

“We want to emulate the precision we’ve seen in oncology,” said Mielke. “It’s no longer ‘breast cancer,’ it’s ER-positive, HER2-negative. That level of biomarker and molecular driven detail is where we’re headed in neurology.”

And yet, systemic barriers remain. Some health systems still lack the infrastructure to integrate blood tests into workflows, and stigma still keeps some patients with cognitive changes from seeking evaluation early enough.

Educate, Implement, Protect

To fully realize the potential of blood biomarker tests, stakeholders across health care must act:

• Educate clinicians on how to interpret and use blood biomarker results.
• Integrate testing into workflows, particularly in primary care.
• Update reimbursement policies to make testing affordable and equitable.
• Ensure legal protections for patients who test positive.
• Combat stigma with public education campaigns about early symptomatic Alzheimer’s disease detection.

“This is a time of excitement – but also uncertainty,” Mielke said. “We’re on the edge of a new diagnostic paradigm. The more we prepare now, the better we’ll serve our patients later.”

The goal is clear: make the early symptomatic Alzheimer’s disease diagnostic journey faster, more equitable, and more accurate – so that millions more people can plan ahead and face the future with dignity. Learn more about implementing blood biomarker tests at timehidesalz.lilly.com.

References

1. Alzheimer's Association. 2025 Alzheimer's disease facts and figures. Alzheimer's Dement. 2025;21(4):e70235. Published 2025 Apr 29. doi:10.1002/alz.70235
2. Hampel H, Jessen F, Cummings J, et al. Blood-based biomarkers for Alzheimer’s disease: mapping the road to the clinic. Alzheimer's Dement. 2024;20(5):e14184. doi:10.1002/alz.14184
3. Quinn TJ, Jessen F, Cummings J, et al. Consensus recommendations on blood-based biomarkers for Alzheimer’s disease: an update from the Global CEO Initiative on Alzheimer’s Disease. J Prev Alzheimers Dis. 2024;11(2):211-222. doi:10.14283/jpad.2024.32
4. Porsteinsson AP, Isaacson RS, Knox S, et al. Diagnosis of Early Alzheimer’s Disease: Clinical Practice in 2021. J Prev Alzheimer’s Dis. 2021;8(3):371-386. doi:10.14283/jpad.2021.23
5. Barthélemy, N.R., Salvadó, G., Schindler, S.E. et al. Highly accurate blood test for Alzheimer’s disease is similar or superior to clinical cerebrospinal fluid tests. Nat Med 30, 1085–1095 (2024). https://doi.org/10.1038/s41591-024-02869-z
6. Schöll, Michael & Vrillon, Agathe & Ikeuchi, T. & Quevenco, F.C. & Iaccarino, Leonardo & Vasileva-Metodiev, S.Z. & Burnham, S.C. & Hendrix, J. & Epelbaum, S. & Zetterberg, H. & Palmqvist, Sebastian. (2025). Cutting through the noise: A narrative review of Alzheimer's disease plasma biomarkers for routine clinical use. The Journal of Prevention of Alzheimer's Disease. 12. 100056. 10.1016/j.tjpad.2024.100056.