As scientists continue to learn more about the potential causes behind Alzheimer’s disease, some recent research has been focusing on looking for the earliest possible warning signs for this type of dementia.
One tool that doctors are beginning to use to help predict a person’s Alzheimer’s disease risk in its earliest stages is through blood tests that search for specific biomarkers in the blood.
Now, a new study published in The Lancet, primarily funded by the National Institutes of Health (NIH), has found that these biomarker blood tests may also help doctors detect very early signs of cognitive decline in midlife adults without a dementia diagnosis.
Researchers believe using Alzheimer’s disease biomarker blood tests in this way may give more credence to initiating healthy lifestyle modifications known to help potentially lower dementia risk.
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For the study, researchers analyzed data from participants of the U.S. Coronary Artery Risk Development in Young Adults (CARDIA) Study. Researchers selected about 1,300 of these study participants with an average age of 61.
Of this pool, 6% showed a high level of the proteins beta-amyloid and tau in their blood, which are considered hallmarks of Alzheimer’s disease.
Scientists found that the participants in this 6% had lower processing speeds and executive function. And when tested five years later, those with high beta-amyloid and tau biomarkers had about 2.5 to 4 times the risk of rapid decline in verbal memory, and around 3 to 4 times the risk of rapid decline in processing speed.
“What we found is that having these (biomarker blood) tests be positive were not common, but if they were, they were associated with worse cognition and greater decline compared to those not positive,” Kristine Yaffe, MD, distinguished professor and vice chair of the Departments of of Psychiatry, Neurology, and Epidemiology at the University of California – San Francisco (UCSF) and senior author of this study, told Medical News Today.
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“More and more people will ask for these tests, and companies are doing direct-to-consumer advertising. So we don’t want to alarm people, but if positive, provide them with guidance (on) how to improve/lower risk for cognitive decline, and maybe in the future consider new medications for Alzheimer’s disease.”
— Kristine Yaffe, MD
MNT spoke with Megan Glenn, PsyD, clinical neuropsychologist in the Center for Memory and Healthy Aging at the Hackensack Meridian Neuroscience Institute at Jersey Shore University Medical Center in New Jersey — who was not involved in this study — about this research.
Glenn said she felt highly encouraged by the study’s findings, as it feels as though multiple lines of research are finally converging.
“We have known for a long time that subtle cognitive changes and biological markers, particularly amyloid accumulation, begin developing decades before a patient meets the criteria for a formal dementia diagnosis,” she explained. “We have been searching for accessible ways to detect these earliest signs during this ‘preclinical’ phase so we can intervene sooner, and this study represents a major step toward making early detection scalable and accessible to the general public.”
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When it comes to diagnosing a person’s Alzheimer’s disease risk as soon as possible, Glenn said we need more precision because having Alzheimer’s biomarkers doesn’t guarantee someone will develop clinical symptoms.
“Amyloid accumulation in the brain is like the kindling, but not the fire — it sets the stage, but doesn’t guarantee progression unless other factors, like tau tangles, are also present,” she detailed. “We need to figure out exactly who among those with early biomarker changes will actually go on to develop dementia.”
“Developing early detection is critical because by the time memory loss and other symptoms are obvious, the brain has already suffered significant, likely irreversible damage,” Glenn continued.
“Historically, many Alzheimer’s treatments — even recently approved medications that successfully clear amyloid — have shown modest clinical effects, potentially because they are given too late in the disease process. If we can accurately identify risk during the preclinical stage, we can potentially intervene with lifestyle changes and/or disease-modifying therapies before permanent damage occurs. It is always better to prevent the damage in the first place than to try to mitigate it after the fact.”
— Megan Glenn, PsyD
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Additionally, researchers believe that by detecting early signs of Alzheimer’s disease, people can better target modifiable risk factors.
“The proteins that cause Alzheimer’s disease take decades to accumulate in the brain,” Yaffe explained. “ The blood tests can detect these proteins — tau and amyloid-beta. So it might be good to detect early so people can lower their risk by lifestyle interventions and possibly drugs. They can also be monitored closely by their clinician.”
MNT spoke with Dung Trinh, MD, an internist for the MemorialCare Medical Group and chief medical officer of the Healthy Brain Clinic in Irvine, CA — who was not involved in this study — and he commented that a blood test like this could make the risk conversation more concrete.
“Many patients hear ‘exercise more,’ ‘control blood pressure,’ ‘sleep better,’ or ‘manage diabetes,’ but those recommendations can feel general or abstract,” Trinh explained. “If a patient has evidence of Alzheimer’s-related biomarker changes, that can create a more personalized and urgent conversation about brain health.”
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“I would explain it carefully: a positive biomarker result does not mean someone has dementia, and it does not predict the future with certainty. But it may suggest that Alzheimer’s-related biology is present, which makes it even more important to aggressively address the factors we can modify.”
— Dung Trinh, MD
In practical terms, Trinh said, that means focusing on blood pressure, cholesterol, diabetes, physical activity, smoking, sleep apnea, depression, hearing loss, social isolation, nutrition, and medication review.
“The (press release) also highlights Dr. Kristine Yaffe’s point that modifiable risk factors — including physical and cognitive inactivity, depression, smoking, and heart health — play an important role in dementia risk,” he added. “The goal is not to scare patients. The goal is to give them agency. A biomarker result should open the door to prevention-oriented care, not fatalism.”
