Could a Blood Test Predict Alzheimer’s Disease Years Before Symptoms?
A simple blood test may eventually help identify older adults who are at higher risk of developing Alzheimer’s-related cognitive impairment years before symptoms appear.
A new study published in JAMA and presented at the Alzheimer’s Association International Conference examined a blood-based biomarker called p-tau217. Researchers found that very high levels of this biomarker were associated with a substantially increased risk of developing cognitive impairment over the following five to 10 years.
The findings are promising — but they also come with an important caution: this test is not currently recommended as a routine screening test for healthy people.
What Is p-tau217?
Alzheimer’s disease is associated with changes in the brain involving two important proteins: amyloid, which can accumulate into plaques, and tau, which can form abnormal tangles associated with damage to brain cells.
p-tau217 is a form of phosphorylated tau that can be measured in the blood. It appears to correlate with Alzheimer’s-related changes occurring in the brain. Researchers are studying whether blood-based biomarkers like p-tau217 can eventually provide a practical way to identify people who are at increased risk.
What Did the Study Find?
Researchers analyzed data from 2,684 older adults who were considered cognitively healthy when they entered long-running Alzheimer’s research studies. Participants had p-tau217 testing at enrollment and underwent regular cognitive assessments.
Among participants with very high p-tau217 levels, the estimated risk of developing cognitive impairment was approximately 38% over five years, increasing to approximately 78% over 10 years. People with very low levels had a much lower risk during the same period.
However, the researchers and outside experts emphasize that these numbers should not be interpreted as an individual’s personal prediction of developing Alzheimer’s disease.
Why Isn’t This a Routine Screening Test Yet?
There are several important limitations. First, not everyone with Alzheimer’s-related brain changes develops dementia — some people can have substantial amyloid accumulation without developing significant cognitive impairment. Second, other health conditions can affect cognition; cardiovascular disease and other causes of cognitive decline may complicate predictions about who will ultimately develop Alzheimer’s disease.
And while researchers had substantial five-year follow-up information, fewer participants had been followed for a full 10 years, making the longer-term estimate less certain. Experts have also noted that current blood tests are not yet precise enough to provide individualized prognostic information for healthy people.
Why Is This Research Important?
The biggest potential benefit may currently be in Alzheimer’s research and drug development. Several clinical trials are investigating whether treatments can prevent or delay Alzheimer’s disease before significant symptoms develop. If effective preventive treatments become available, clinicians will need practical ways to identify people who might benefit — and a reliable blood biomarker could eventually make that process much easier than relying on more invasive or expensive testing.
What Should Healthy Older Adults Do Now?
For now, experts involved in the research are discouraging healthy people from seeking p-tau217 testing simply because they are worried about developing Alzheimer’s disease. Importantly, a test result today would generally not change what experts recommend for maintaining brain health, including:
- Eating a balanced diet
- Getting regular physical activity
- Prioritizing adequate sleep
- Staying socially and mentally engaged
- Managing blood pressure, cholesterol, diabetes and other cardiovascular risk factors
- Discussing new or concerning cognitive symptoms with a healthcare professional
The Bottom Line
Blood-based Alzheimer’s biomarkers represent one of the most exciting developments in dementia research. A test such as p-tau217 may eventually help clinicians identify people at increased risk before symptoms develop, particularly if effective preventive treatments become available. But today, a promising predictive test is not the same as a definitive diagnosis or a reason for routine screening in healthy individuals.
At Orleans Family Health Clinic, we encourage patients with concerns about memory or cognitive changes to discuss them with their healthcare provider. The appropriate assessment depends on the individual’s symptoms, medical history and overall health.
Research is moving quickly. The goal is not simply to predict Alzheimer’s disease — but ultimately to give patients something meaningful they can do with that information.
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Disclaimer: The medical information on this site is provided as an information resource only and is not to be used or relied on for any diagnostic or treatment purposes. This information does not substitute for professional diagnosis and treatment. Please do not initiate, modify, or discontinue any treatment, medication, or supplement solely based on this information. Always seek the advice of your healthcare provider first. Full Disclaimer.
