Blood Test May Predict Alzheimer’s Onset
A straightforward blood test could forecast not only the likelihood of developing Alzheimer’s disease but also estimate when symptoms might start to manifest.
Researchers at Washington University School of Medicine in St. Louis aimed to investigate if certain proteins could serve as a “biological clock” for predicting symptom onset related to the disease.
One specific protein, known as p-tau217, creates “tangles” in the brain, interrupting communication between nerve cells. In healthy brains, tau plays a role in stabilizing nerve cell structures.
Typically, brain scans can detect these tangles for diagnosing Alzheimer’s. Early findings suggest that the same approach could help outline the progression of the disease.
Imaging tests can be complicated and pricey, prompting researchers to explore whether blood tests could observe similar proteins and yield comparable information.
The study, published in Nature Medicine, evaluated data from over 600 older adults engaged in two long-term Alzheimer’s research projects.
By reviewing blood samples and cognitive performance across several years, the research team discovered that p-tau217 levels consistently increased well before any noticeable memory decline began.
Using this information, they developed a model that estimates when symptoms might appear, with an error margin of roughly three to four years.
Dr. Keren K. Petersen, a lead author of the study, explained that this single blood test measuring p-tau217 could provide an initial sense of when an individual might develop Alzheimer’s symptoms.
The research highlighted that older adults see symptoms emerging more quickly once p-tau217 levels become abnormal. For instance, individuals who first showed abnormal levels around age 60 typically did not develop symptoms for about 20 years. However, those who exhibited abnormal p-tau217 levels at age 80 often started showing symptoms roughly a decade later.
This observation indicates that both age and changes in brain condition can affect the speed at which Alzheimer’s symptoms surface, according to the researchers.
Dr. Rebecca M. Edelmeyer from the Alzheimer’s Association noted this could reshape how clinical trials are planned and how clinicians identify individuals at risk for cognitive decline long before it happens.
Blood tests are generally less costly and easier to administer than brain scans or spinal fluid tests. They could play a significant role in helping doctors spot individuals who might benefit from early intervention.
While promising, the study has limitations. Petersen pointed out that their predictions were valid only for those whose p-tau217 levels fell within a certain, albeit broad, range. Additionally, the population studied was somewhat homogeneous—healthy, educated, and lacking diversity—raising concerns about how well the results would apply across different groups.
Even though the researchers mentioned the potential for home blood tests, they cautioned against seeking such tests independently. Dr. Suzanne Schindler, a co-author, advised that non-cognitively impaired individuals should not undergo Alzheimer’s biomarker testing at this time.
Petersen acknowledged the experimental nature of these findings, emphasizing the need for improvement in accuracy before they can influence clinical practice.
Looking ahead, the team aims to enhance the test’s precision by investigating other proteins tied to Alzheimer’s and to include a more diverse participant pool.
Currently, two large clinical trials are in progress, focusing on whether individuals with elevated p-tau217 levels could benefit from treatments with either lecanemab or donanemab—approved medications aimed at reducing brain plaques associated with Alzheimer’s.
The goal is to determine whether initiating treatment earlier could enhance the drug’s efficacy.
Petersen expressed optimism, stating that combining various blood and imaging biomarkers with p-tau217 may refine predictions about symptom onset further and contribute to better models for individual assessment.
