Alzheimer’s disease continues to be one of the most daunting public health challenges of our time. In the United States alone, one in nine people over age 65 is living with Alzheimer’s dementia. By 2060, that number is projected to nearly double, reaching 13.8 million individuals. In 2025, the cost of caring for people with Alzheimer’s and related dementias is expected to top $384 billion — and that figure doesn’t begin to capture the emotional toll on families and caregivers.
For decades, progress in treating and diagnosing Alzheimer’s lagged behind other diseases. But today, we stand at the threshold of a new era. Disease-modifying therapies are now available for people with mild cognitive impairment (MCI), an early stage of Alzheimer’s disease, offering new hope for slowing disease progression, including FDA-approved treatments such as lecanemab and donanemab. Simultaneously, innovations in biomarker science, particularly in cerebrospinal fluid (CSF) and blood, are reshaping how and when we detect the disease and are expanding Alzheimer’s testing beyond specialty care. This shift allows primary care providers to help triage symptomatic patients and facilitate detection of Alzheimer’s in early stages.
Why biomarkers matter
Traditional Alzheimer’s diagnosis has long relied on cognitive assessments and clinical symptoms, often leading to diagnosis well after significant neurodegeneration has occurred. Biomarkers are changing that.
A growing body of evidence supports the use of key biomarkers, including amyloid-beta and tau proteins, as sensitive and specific indicators of Alzheimer’s pathology, considering that the changes often begin before symptoms appear. Biomarker tests can detect these proteins very early in the disease and have been shown to improve diagnostic accuracy significantly. That shift is critical: early detection opens the door to timely interventions, e.g., lifestyle changes, access to treatment, and research participation.
Understanding the biomarker landscape
The field of Alzheimer’s disease biomarkers continues to evolve rapidly, with multiple assays cleared for clinical use and others under investigation. Several biomarkers have been extensively studied and are commonly referenced in research and clinical discussions:
- Beta-amyloid 1-42 (Aβ42): The accumulation of this peptide in the brain as amyloid plaques is a defining feature of Alzheimer’s disease. In both cerebrospinal fluid (CSF) and blood, reduced levels of Aβ42 may reflect amyloid deposition in the brain.
- Phosphorylated tau 181 (pTau-181): In Alzheimer’s disease, tau proteins become abnormally phosphorylated, contributing to the formation of neurofibrillary tangles. Phosphorylation at threonine 181 is one of the most studied tau modifications. pTau-181 can be measured in CSF and, more recently, in blood, where it has demonstrated utility in identifying Alzheimer’s-related pathology. As the U.S. Food and Drug Administration (FDA) clears blood-based tests, clinicians are better able to evaluate Alzheimer’s disease pathology in symptomatic adults undergoing assessment for cognitive impairment. Blood-based biomarkers will increasingly enter clinical workflows, including primary care settings, in order to help guide decisions about follow-up testing such as CSF analysis or imaging.
- Phosphorylated tau 217 (pTau-217): Phosphorylation at threonine 217 represents another tau biomarker under active study. Plasma pTau-217 has shown strong performance characteristics in identifying Alzheimer’s pathology and correlates with amyloid burden. An FDA-cleared test combining pTau-217 with Aβ42 into a ratio is available for use in appropriate clinical contexts.
- Total tau (tTau): Total tau levels in CSF are considered a marker of neuronal injury. Elevated tTau can support the assessment of neurodegeneration, although it is not specific to Alzheimer’s disease and may be observed in other neurological conditions.
These and other emerging biomarkers are reflected in evolving research and clinical guidance. Professional organizations, including the Alzheimer’s Association and other expert groups, continue to update recommendations regarding the role of biomarker testing in clinical trials and in routine clinical practice as evidence develops.
What’s next: From detection to action
Detecting amyloid pathology is a critical step in the path to an early and accurate Alzheimer’s diagnosis. A timely diagnosis empowers individuals and their care teams to consider several evidence-based interventions available:
- Lifestyle changes such as diet, exercise, and cognitive training, which may delay onset or slow progression
- Initiation of disease-modifying therapies for those in early stages, when they are most effective
- Opportunities to join clinical trials, giving patients access to cutting-edge treatments and contributing to future breakthroughs
Much like advances seen in precision oncology, Alzheimer’s care is entering an era of precision medicine. Biomarker tests’ ability to detect multiple pathologies co-existing in Alzheimer’s not only enable early diagnosis, but could guide personalized therapeutic decisions.
Staying ahead of the curve
As blood-based biomarkers (BBBMs) gain FDA clearances and public attention, it’s critical for the medical community to focus on the scientific rigor, clinical utility, and appropriate use of these tools. While blood-based tests hold tremendous promise for broadening access, CSF and imaging (i.e., amyloid PET scans) remain the more specific modalities and will likely be needed for some patients for the foreseeable future.
As research continues across CSF, PET, and blood-based biomarkers, the goal remains to improve early, accurate diagnosis and disease monitoring. The FDA clearance of blood tests is a significant step forward. Growing availability of these types of tests helps to expand access to testing and supports clinicians across primary and specialty care settings as they navigate this rapidly transforming field.
A future within reach
Alzheimer’s diagnostic testing complements the clinical diagnosis with an objective, biological assessment. As we look ahead, we envision a healthcare landscape in which biomarker-based testing for Alzheimer’s is accessible and routinely performed.
As new diagnostics and therapies continue to advance in lockstep, we’re moving closer to what patients and families have long hoped for: answers earlier, actions sooner, and outcomes that reflect the full power of modern medicine.
Photo: Andreus, Getty Images
Maria-Magdalena Patru, MD, PhD, is an experienced physician-scientist, with over 17 years in the field of laboratory medicine and more than 14 years in the in-vitro diagnostics industry. Currently serving as the Senior Scientific Manager for neurology at Roche Diagnostics US, she leads a team developing medical strategies for neurology biomarkers, primarily focusing on Alzheimer’s. Her background includes a medical degree, Laboratory Medicine training, a PhD in Microbiology and Immunology, a clinical laboratory fellowship, and extensive experience in medical and scientific affairs, particularly in IVD product development, validation, and clinical trials.
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