Medical researchers are advancing the use of blood-based biomarkers to identify Alzheimer’s disease years before clinical symptoms emerge. Recent studies highlight two distinct diagnostic pathways: the measurement of the p-tau217 protein and the analysis of circular RNAs (circRNAs). These developments aim to provide less invasive, more accessible alternatives to traditional diagnostic methods like PET scans and lumbar punctures.
The Role of p-tau217 in Early Detection
According to research, the p-tau217 biomarker shows significant potential for predicting the accumulation of beta-amyloid plaques in the brain, which are precursors to dementia. Data indicate that cognitively healthy older adults with elevated levels of p-tau217 had a 38% higher estimated probability of developing early signs of dementia over five years. Over a ten-year period, that risk increased to 78%, though researchers note that data for the longer interval are less robust.
Rachel Buckley, an associate professor of neurology at Harvard Medical School, explains that p-tau217 helps identify the moment beta-amyloid begins to trigger the spread of the disease. While beta-amyloid plaques can accumulate decades before memory loss, the presence of these proteins alone does not guarantee future cognitive impairment. However, when combined with early-stage tau, the protein appears to accelerate the disease process. Experts emphasize that this test should not be used in isolation but as part of a comprehensive diagnostic process that includes cognitive testing.
Circular RNAs as Dynamic Indicators
National Institutes of Health (NIH) suggests that certain circular RNAs (circRNAs) in the blood may be more sensitive to early clinical manifestations than traditional markers. Researchers analyzed blood data from over 1,200 individuals and identified a set of 34 circRNAs associated with Alzheimer’s.
Unlike beta-amyloid, which accumulates slowly, circRNAs are described as more dynamic, reflecting more recent brain activity. The study found these molecules could potentially predict the onset of symptoms two to four years in advance. Carlos Cruchaga, the study’s corresponding author, noted that while the new circRNA model performs similarly to p-tau217-based models, it appears to be a stronger predictor of progression to symptomatic Alzheimer’s. These findings may prove invaluable for selecting patients for clinical trials and monitoring therapeutic responses, particularly for treatments targeting beta-amyloid.
Advancements in Clinical Access
The landscape of Alzheimer’s diagnosis is shifting toward broader accessibility. In Brazil, DB Diagnósticos has introduced a blood-based biomarker test, marketed under the “Memora” line, which is now processed entirely within the country at a facility in Sorocaba, São Paulo. This development eliminates the previous requirement to send samples to international laboratories.
Rodrigo Faitta Chitolina, product supervisor at DB Diagnósticos, stated that this advancement allows for a more accessible, scientifically backed tool to support clinicians. The test is intended for patients with mild cognitive impairment or suspected dementia, rather than for cognitively healthy individuals.
Clinical Context and Limitations
Despite these technological strides, medical professionals urge caution. Richard Isaacson, director of research at the Institute for Neurodegenerative Diseases, and other experts maintain that these blood tests should not be used in isolation for risk assessment. Furthermore, the global scale of the challenge remains significant; the World Health Organization (WHO) estimates that approximately 57 million people currently live with dementia, with Alzheimer’s accounting for up to 70% of cases. With that number projected to exceed 150 million by 2050, experts like Bryan Woodruff of the Mayo Clinic emphasize the urgent need to expand the number of professionals capable of diagnosing the disease.
As researchers continue to develop practical clinical assays for these biomarkers, the goal remains to integrate these tests into routine practice, similar to how clinicians currently measure risks for diabetes or heart attacks.
Key Diagnostic Developments
| Biomarker | Primary Function | Clinical Status |
|---|---|---|
| p-tau217 | Predicts beta-amyloid accumulation | Used for identifying risk in symptomatic patients |
| circRNAs | Reflects recent brain activity | Research stage; potential for predicting onset |
Sources: R7 G1 CNN Brasil Novo Momento