Could a Simple Blood Test Reveal Your Dementia Risk?

Yahoo

05-05-2025

Despite a lot of advancements in our understanding of dementia over the past few decades, doctors still don't have a reliable way to tell who will develop the devastating condition. There's been quite a bit of research into major risk factors, including microplastics exposure, shingles vaccines, sleep quality, and more.
Now, a new study suggests that there may be important clues on how your sex, age, and hormonal changes impact certain biomarkers for dementia that can be picked up in a blood sample. However, that doesn't mean a simple blood test can predict dementia risk, which further emphasizes the fact that they should not be the sole test doctors rely on for assessing risk.
One positive thing we can learn from the study: Neurologists say the findings underscore how individual risk factors for the disease can be, especially between men and women. Here's what the study found, plus what they want you to know.
Meet the experts: Clifford Segil, DO, is a neurologist at Providence Saint John's Health Center in Santa Monica, CA; Amit Sachdev, MD, MS, is the medical director in the Department of Neurology at Michigan State University.
The study, which was published in the journal Neurology, analyzed data from a 17-year study and compared 513 people who developed dementia during the study period to 513 people who did not.
The researchers also took blood samples during the study to look at three specific biomarkers: neurofilament light chain proteins, glial acidic proteins, and phosphorylated tau 181.
Here's a quick breakdown of these terms, in case you're unfamiliar: Neurofilament light chain proteins are detected in blood when nerve cells are injured or die; Glial acidic proteins are released when cells try to repair an injury; And phosphorylated tau 181 is tied to the formation of amyloid proteins in the body, which are linked with Alzheimer's disease.
The researchers compared the levels of these biomarkers in both groups of participants, and discovered that aging was linked with higher levels of all three, meaning the levels were raised in all participants, not just those with dementia.
However, they also found that female study participants, especially those who hadn't gone through menopause yet, had higher levels of glial acidic proteins, while male participants had higher levels of neurofilament light chain proteins. And participants who had APOEe4, a genetic biomarker that is linked with a strong risk of developing Alzheimer's disease, had higher levels of phosphorylated tau 181 and glial acidic proteins.
Basically, this study showed that there are sex differences in these biomarkers as we age and go through menopause, but we don't yet know what those differences mean since the results were uniform for those with and without dementia.
There's a lot happening with these findings and it's understandable to get lost in the weeds here. But neurologists say the data show that the risk of developing dementia depends on a range of factors, and that you can't count solely on a blood test to determine your risk.
'Even with individuals who have a very strong family history of dementia, there is not a guarantee that they will be affected later in life,' says Amit Sachdev, MD, MS, medical director in the Department of Neurology at Michigan State University. 'This [research] suggests that the path to developing dementia is somewhat different for each person. If we can understand the risk factors better, we can optimize the approach for a specific person.'
Clifford Segil, DO, a neurologist at Providence Saint John's Health Center in Santa Monica, CA, says that it 'makes sense' to look at gender-specific issues like menopause when evaluating someone's dementia risk.
While Dr. Segil says that it's unlikely that these findings will eventually lead to different blood tests for men and women, he stresses that the results underscore the need for dementia to be diagnosed from more than a blood test. 'There remains concern [that] dementia blood biomarkers have a high number of false positives, or are positive in people without any dementia,' he says. 'Studies like this support clinical neurologists' caution in using a blood test to diagnose a patient with dementia.'
Dementia diagnoses are usually done through several tests, usually an MRI of the brain, PET scan, blood work, and a lumbar puncture to analyze cerebrospinal fluid, Dr. Sachdev says.
Doctors will also usually recommend neuro-psychiatric testing to see if the brain is performing the way it should, he says. And after pulling all of those results together, they'll usually make a diagnosis.
Ultimately, if you're concerned that you or a loved one might have dementia, Dr. Segil says it's crucial to see a neurologist for an evaluation. There are some reversible causes of memory loss, and getting to the bottom of what's behind yours can go a long way toward a proper diagnosis and treatment, he points out.
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