A new study suggests that a straightforward blood test could forecast not just the risk of developing Alzheimer’s disease but also the approximate year signs will manifest.
Researchers from Washington University School of Medicine in St. Louis investigated whether certain protein levels in the blood could serve as a “biological clock” to predict when Alzheimer’s symptoms appear. One key protein, p-Tau217, is known to form “tangles” in the brain, which interfere with communication among nerve cells. While tau usually supports nerve cell structure, these tangles are problematic.
Traditionally, brain scans have been utilized for diagnosing Alzheimer’s by detecting these tangles. However, earlier investigations hinted that blood tests measuring the same proteins might yield comparable insights. Given that imaging tests can be intricate and costly, the research team aimed to simplify this with blood analysis.
In their study, published in *Nature Medicine*, they reviewed data from over 600 older adults involved in long-term research projects focused on Alzheimer’s. By comparing blood samples with cognitive performance data amassed over several years, they discovered that p-Tau217 levels exhibited a “remarkably consistent” rise long before memory issues set in.
The researchers developed a model that estimated when symptoms would emerge based on the patient’s age and protein levels, estimating a margin of error between three to four years.
“We demonstrated that a single blood test measuring p-Tau217 can provide a rough timeline for when someone is likely to show symptoms of Alzheimer’s,” said Dr. Keren K. Petersen, lead author and neurology lecturer at Washington University.
Notably, they found that the progression of symptoms is often swifter in older individuals once p-Tau217 levels become abnormal. For instance, individuals who showed abnormal p-Tau217 levels at age 60 might not experience symptoms for another 20 years, while those showing abnormalities at age 80 may begin to see symptoms develop about a decade later.
This suggests that both age and disease-related brain changes could affect how quickly Alzheimer’s symptoms appear. Dr. Rebecca M. Edelmeyer from the Alzheimer’s Association noted that these findings could revolutionize the design of clinical trials and methods for identifying individuals at high risk of cognitive decline.
Interestingly, blood tests tend to be more affordable and straightforward compared to brain scans or spinal fluid analysis. In the future, they could assist healthcare providers in identifying candidates for early treatment.
However, the study has some limitations. The predictive model was only applicable to those with p-Tau217 levels within a specific range, which was relatively narrow. Additionally, since the study group was largely healthy and well-educated, the findings may not apply broadly.
Although the researchers mentioned the possibility of home blood tests, they discourage anyone from self-testing for Alzheimer’s biomarkers without professional guidance. Dr. Suzanne Schindler from the University of Washington emphasized that such testing is not recommended for individuals without cognitive impairment.
Petersen acknowledged that the current findings remain experimental and stressed the need for ongoing refinement. He expressed hope for developing more precise models in the future.
Looking ahead, the team aims to enhance the test’s accuracy by examining other proteins related to Alzheimer’s. They also underscored the importance of involving a more diverse participant pool in future studies.
Meanwhile, two significant clinical trials are already in progress to evaluate whether individuals with elevated p-Tau217 can benefit from treatment using specific Alzheimer’s drugs before the onset of symptoms. The medications, lecanemab and donanemab, have been approved to help reduce abnormal brain plaque, and early intervention may increase their effectiveness.
Petersen concluded that combining p-Tau217 with other biomarkers and cognitive assessments could improve the accuracy of predicting Alzheimer’s symptom onset, paving the way for even better solutions for potential patients.
