Blood Test May Predict Alzheimer’s Risk in Older Adults
Researchers have announced that a blood test could potentially indicate whether seemingly healthy older adults might develop Alzheimer’s symptoms within the next five to ten years. This information could either bring comfort or cause concern, depending on how one views it. Nevertheless, it presents a promising opportunity to expedite drug development by helping to identify individuals at high risk for participation in studies related to Alzheimer’s treatments and preventive measures.
Current large-scale clinical trials are investigating whether specific medications might delay or prevent the onset of the disease. If any of these trials prove successful, doctors will need a straightforward way to determine which patients should try these medications.
However, the researchers behind this study caution that it’s premature for healthy individuals to pursue the p-tau217 test, which is primarily used to diagnose those already experiencing cognitive issues. Dr. Reisa Sperling, senior author and head of the study at the Mass General Brigham Neuroscience Institute, emphasized waiting until there are actionable steps to be taken. She recommends maintaining a healthy lifestyle through good nutrition, sufficient sleep, regular exercise, and staying socially engaged.
The study revealed that symptom-free older adults with elevated p-tau217 levels had a 38% chance of developing cognitive impairment over a five-year span, which increased to 78% by the ten-year mark.
Published in JAMA and presented at the Alzheimer’s Association International Conference in London, the research explores the underlying causes of Alzheimer’s, which remains somewhat ambiguous. The disease is marked by amyloid plaques and tau tangles in the brain. The p-tau217 test gauges a specific form of tau that correlates with the extent of plaque accumulation and offers insights regarding tau tangles, according to Sperling.
Study Details
The Mass General Brigham team examined data from 2,684 older adults who were healthy at the onset of long-term Alzheimer’s studies, taking the p-tau217 blood test when they enrolled and undergoing yearly cognitive assessments. From initial enrollment in 2004 until last year, about 478 participants developed cognitive impairment.
Interestingly, those with very low p-tau217 levels demonstrated a correspondingly low risk of cognitive impairment over the subsequent five to ten years. There is a complexity in predicting Alzheimer’s, as many individuals show high levels of amyloid plaques without developing dementia. One prevailing theory suggests that this amyloid buildup might eventually cause an abnormal tau to generate tangles, leading to symptoms.
Sperling indicated that the blood test results reveal new insights. While varying intermediate levels of p-tau217 indicated increasing risk, only the highest levels appeared to relate closely to evidence of a critical threshold.
Calls for Caution
While the study received praise from scientists not affiliated with it, they expressed some reservations. One issue is that only a small number of participants were followed for a full decade, which casts some doubt on the reliability of the ten-year risk estimate compared to the five-year one.
Other factors could also cloud predictions. Older adults might be vulnerable to dying from other causes or suffer from heart conditions that could lead to vascular dementia instead of Alzheimer’s, as noted by Drs. Suzanne Schindler from Washington University in St. Louis and David Wolk from the University of Pennsylvania in a commentary in JAMA.
They pointed out that the blood tests are not yet reliable enough for personalized prognosis. Still, they acknowledged that this new research offers a significant piece to the larger puzzle.
Jessica Langbaum from the Banner Alzheimer’s Institute in Phoenix mentioned that many people are already requesting the blood test due to family histories of Alzheimer’s, a move she currently advises against. “These findings are pretty compelling,” she said, noting that a predictive blood test could become crucial—if ongoing studies eventually discover effective drugs that could intervene before symptoms arise.
