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What Are Biomarkers and How Do They Impact Brain Disease Research?

Biomarkers are crucial to diagnosing brain diseases and developing new treatments. Learn about types of biomarkers and how they drive research progress.

Biomarkers have played a big role in some of the most significant brain disease research breakthroughs of the last year — from researchers developing a new Parkinson’s biomarker test to using measurements of toxic protein buildups to test newly approved Alzheimer’s drugs. But what is a biomarker exactly, and why are biomarkers so useful to doctors and brain disease researchers? 

In addition to allowing doctors to better diagnose and treat diseases like Alzheimer’s and Parkinson’s, biomarkers drive research by helping scientists understand the causes and progression of diseases. They also aid in the development of new treatments. Read on to learn about different types of biomarkers and how biomarker research takes us one step closer to life without brain disease.

What Are Biomarkers?

A biomarker is any measurable substance or biological process that illustrates something happening in the body. Biomarkers may show the presence of a disease, the risk of developing a disease, or a particular response the body is having to medications or environmental factors. Think of them as biological clues that provide critical information about our health and illnesses.

Biomarkers may be substances found in the blood or spinal fluid (called fluid biomarkers), such as the presence of toxic protein clumps in people with Alzheimer’s disease or blood sugar levels for someone with diabetes. Additionally, biomarkers can be particular genes, testable measurements like blood pressure, or even test results themselves, like images from an MRI or CT scan.

Why Are Biomarkers Useful?

Discovering a biomarker for a disease that isn’t easy to diagnose is like finding a fingerprint for a specific condition. This is helpful in many ways, but primarily in the diagnosis and treatment of diseases.

Biomarkers Aid in Disease Diagnosis

Biomarkers often give doctors a more clear-cut way to identify and diagnose a disease as opposed to making a diagnosis based on symptoms alone.

This is especially important for neurodegenerative diseases like Alzheimer’s, Parkinson’s, LBD, and others. In many of these diseases, symptoms don’t appear until after the disease has already been present for many years. By the time doctors can make a diagnosis based on symptoms, significant and often irreversible damage has already been done to the brain. On the other hand, if doctors can use biomarkers to detect and diagnose a disease early, it is much easier to start early treatment and prevent the disease from progressing into more severe stages.

Biomarkers Help Direct and Monitor Treatments 

Additionally, some types of biomarkers allow doctors and researchers to monitor the effectiveness of treatments over time.

For example, last year the FDA approved several new Alzheimer’s medications based on research showing that they effectively reduced the amount of toxic amyloid proteins in the brain. These new drug developments were made possible by prior research that linked clumps of this specific type of protein to Alzheimer’s disease. Based on this earlier discovery, researchers knew they could test for a specific biomarker — amyloid proteins — to determine the presence of Alzheimer’s and that drugs targeting this protein may slow the progression of the disease.

Types of Biomarkers

Biomarkers can take many different forms and serve a range of different purposes. For example, fluid biomarkers like those discussed above are substances that can be detected in blood, spinal fluid, or other bodily fluids through testing. Genetic biomarkers are specific characteristics found in DNA (or RNA) that indicate a higher risk of developing certain diseases or disorders. Genetic biomarkers are relatively new, having been identified more and more within the past 20 years with the completion of the Human Genome Project.

Additionally, the FDA defines seven different types of biomarkers based on the specific ways they help doctors and researchers understand diseases:

  • Diagnostic biomarkers, as described above, indicate the presence of a disease in the body. 
  • Monitoring biomarkers can be repeatedly tested over time to track the progress of a disease. (Many other types of biomarkers listed here can serve as monitoring biomarkers when tracked consistently over time.)
  • Response biomarkers (sometimes called pharmacodynamic biomarkers) specifically show the body’s response to certain treatments. For example, the changes in protein levels used to approve the new Alzheimer’s drugs mentioned above would be considered response biomarkers, because the changes in protein levels occurred in response to drug treatment. 
  • Susceptibility/Risk biomarkers show whether a person is at a higher-than-average risk of developing a disease. For example, specific gene mutations linked to a disease like spinal muscular atrophy may be used as risk biomarkers.  
  • Predictive biomarkers help doctors and researchers determine whether a person is likely to respond to treatment. (This is different than response biomarkers, which track a person’s actual response to the treatment itself over time.) They are especially important for researchers developing new types of therapies for diseases. 
  • Prognostic biomarkers are used to predict the progress of a disease or the likelihood of a disease recurring or worsening in people who have already been diagnosed. 
  • Safety biomarkers help monitor whether a person is likely to develop complications from a specific treatment or exposure to a toxic substance.

Biomarkers Can Drive Progress in Other Research Areas

Finding a new biomarker for one disease may also shed light on other related diseases. For example, in partnership with the Alzheimer’s Association, The Michael J. Fox Foundation for Parkinson’s Research, and the American Academy of Neurology, the American Brain Foundation is currently funding a Cure One, Cure Many Award to find a biomarker for Lewy body dementia

Because LBD shares many symptoms with other types of dementia, identifying a blood-based biomarker for LBD would help doctors make a more accurate diagnosis and reduce cases of LBD being misdiagnosed as Alzheimer’s or another similar disease. Additionally, research that uncovers an LBD biomarker may also offer information scientists can use to better understand how diseases like Alzheimer’s and LBD are related.

This is one of the reasons we fund research across the full spectrum of brain diseases and disorders — because insights into the cause or treatment of a disease often have ripple effects across many other research areas. 

The American Brain Foundation knows that when we find the cure for one brain disease, we will find cures for many others. Learn more about the brain disease research we fund, or donate today to support the cures and treatments of tomorrow.