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Early detection of Alzheimer’s disease can help doctors design a treatment plan that slows the progression of the disease. However, there is currently no single test that proves a person has Alzheimer's. While physicians can usually determine if a person has dementia, it may be difficult to determine if it's Alzheimer's.

That’s because diagnosing Alzheimer's involves a complete assessment that considers all possible causes. “Currently, it is diagnosed using cognitive assessments, evaluations by your physician and a brain scan,” explains Rebecca Edelmayer, Ph.D., Director of Scientific Engagement at the Alzheimer's Association.

A new Alzheimer’s blood test is showing promise. It may soon be able to help experts spot changes in the brain that lead to Alzheimer’s. This would help doctors understand whether or not dementia symptoms are caused by Alzheimer’s disease in more detail.

Exciting Changes in Alzheimer’s Research

The results from a new study published online in the science journal Nature, says a simple blood test might be able to tell if a person will develop Alzheimer’s. The test may detect a person's risk up to 16 years before symptoms begin.

A team of international researchers studied neurofilament light chain (NfL), which is a protein that can be detected in the blood. “It is being tested as an early biological marker of Alzheimer’s disease,” explains Edelmayer. “Higher levels of it in the blood have been associated with cognitive decline and brain shrinkage in research studies.”

NfL is not a specific marker for Alzheimer’s disease. Edelmayer says many factors can increase NfL in your bloodstream. Inflammation and head injuries have been linked to increased Alzheimer's risk and can also increase your NfL. “That’s why it’s important to continue studying NfL. We may better understand its relationship to Alzheimer’s disease,” says Edelmayer.

In the latest study, scientists measured the rate of change in NfL for 405 individuals from around the world. They examined NfL protein levels in the blood, studied brain imaging and performed cognitive tests every two and a half years on average over the last seven years. They determined that NfL protein levels had a direct link to Alzheimer’s. The study is ongoing.

In order to diagnose or predict Alzheimer’s, more research is needed to perfect an accurate test. Currently, a patient cannot visit their doctor and ask for a blood test for Alzheimer’s. However, the hope is that studies such as this one may someday lead to patients having that ability.

In addition to the ongoing work on NfL, other scientists are developing blood tests for amyloid and tau proteins. These form the plaques and tangles that are hallmark changes of Alzheimer's disease in the brain. “Early results suggest that blood-derived amyloid levels may be useful as a quick and inexpensive test for amyloid buildup in the brain,” says Edelmayer. “This may someday let experts identify people who are at higher risk of Alzheimer's early in the process.”

Read: New Thinking on the Causes of Alzheimer’s

Other Testing Options for Alzheimer's Disease

"There is no single gene that determines you will absolutely, or absolutely not, develop Alzheimer’s disease," says Scott Kaiser, MD, a family physician and geriatrician at Providence Saint John’s Health Center in Santa Monica, CA. There are many genes that seem to contribute to the overall risk.

The most common gene associated with late-onset Alzheimer’s disease (the most common form of Alzheimer’s) is the apolipoprotein E (APOE) gene. Kaiser says there are different forms of the APOE gene. “Tests are widely available which can tell you which variants of the gene you have. Depending on the variant, you may have a reduced, normal, increased, or significantly increased risk of developing the disease.”

To provide information about those genes, some home DNA testing companies associated with genealogy provide a glimpse into the risk of Alzheimer’s disease. Currently some companies like 23andMe test for variants in the APOE gene, which may indicate a risk of late-onset Alzheimer’s disease.

"These tests are safe and reliable," says Kaiser. However, it’s important to weigh the many potential consequences before making the decision to pursue genetic testing since there can be emotional impacts for you or your family.

Aside from efforts to develop a single diagnostic test, researchers are working on “precision medicine”. This combines multiple nuggets of information like lab tests to personalize a person’s risk of Alzheimer’s. "It can also help doctors provide personally tailored recommendations for prevention and/or treatment to try and avoid Alzheimer's," says Kaiser.

Kaiser explains that, “Alzheimer’s disease is associated with lifestyle and environmental factors. The goal is to intervene and address such factors to reduce the risk of ever developing symptoms, or even, prevent the condition altogether.”

Read: Slowing the Progression of Early-Onset Alzheimer’s

Help Find a Cure for Alzheimer’s Disease

Researchers need volunteers for clinical trials to continue developing Alzheimer’s disease detection tools. “Without participation in clinical trials, finding a cure for Alzheimer’s is nearly impossible,” says Edelmayer. To encourage people to participate in research, the Alzheimer’s Association launched TrialMatch®. This clinical study matches both healthy and cognitively impaired volunteers with clinical studies in their area.

Read: Can Artificial Intelligence Lead to Earlier Alzheimer’s Detection?

Reduce Your Risk of Alzheimer’s

While experts work to develop a cure for Alzheimer’s, you can reduce your risk of Alzheimer's disease with lifestyle changes. A 2015 study found people with variants of the APOE gene that indicate a risk for Alzheimer’s can reduce that risk by lowering cholesterol levels. Kaiser says, "Daily exercise, and following a healthy diet, are two of the easiest ways to do that. Along with helping maintain healthy cholesterol, those activities are believed to be linked to preventing the development of Alzheimer’s." So take charge of your heart and brain health by making a few small changes to your lifestyle today.


Study in Nature


2015 study

About the Author(s)

For over two decades, Gina Roberts-Grey has pored over studies and interviewed leading health experts on topics ranging from healthy aging, caregiving and longevity. Having been an active caregiver to her grandparents who lived into their 90’s, Gina is passionate about supporting caregivers through their journeys. Her work has been featured in publications like Woman’s Day, AARP, Oprah, Neurology Now and many more.

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