Simple Blood Test Can Predict Brain Diseases Years Before Symptoms, Says Neurologist

“Would you take this test if it could give you a warning sign years before symptoms?” asked Dr Jay Jagannathan on social media. The US-based neurologist has highlighted the potential of the Neurofilament

Light Chain, or NfL blood test, which is super useful in predicting future brain diseases. “Neurofilament light chain, a marker of nerve cell injury, is emerging as one of the most powerful predictors of brain health. Elevated levels are linked to Alzheimer’s, Parkinson’s, multiple sclerosis, stroke, and even traumatic brain injury,” Dr Jagannathan told his followers on Instagram. What makes it significant, he explained, is that “you could feel ‘fine’… but NfL can already be sounding the alarm. Why it matters: nerve cells don’t repair easily. Elevated NfL means silent but ongoing brain damage — long before symptoms appear,” he added.

Why is NfL important?

NfL is a protein found in the axons of neurons that serves as a biomarker for neuronal damage in various neurological conditions. Doctors say elevated levels of NfL in your blood and cerebrospinal fluid indicate axonal injury or neurodegeneration – making it a valuable tool for monitoring disease progression, assessing the effectiveness of treatments, and providing prognostic information. While its levels may not be specific to one condition, the measurement of NfL in your blood is less invasive than CSF sampling and provides a way to detect and manage a wide range of neurological diseases.

How does NfL work as a biomarker?

Under normal conditions, small amounts of NfL get released into the brain and bloodstream. So, when the neurons or their axons get damaged or degenerate, larger quantities of NfL get released into the interstitial fluid, CSF, and blood. Experts say measuring NfL in these fluids provides an indicator of the extent of neuronal damage.

What do NfL markers indicate?

NFL is used by doctors in adults through:

Healthy adults

NFL stays low

Higher than age-based normal

Red flag for nerve damage

Rising over time

It means there is an active disease, even before MRI picks up anything or symptoms start

What are the applications of NfL in clinical practice?

According to experts, NfL levels predict the course and severity of neurological conditions. It also allows for ongoing tracking of disease activity, especially for conditions like MS. Depending on what the NfL levels are, the test can help monitor how well treatments are working to reduce neuronal damage. Although not disease-specific, high NfL levels can signal potential neurological issues, prompting further investigation. Since NfL blood tests are less invasive than other ways of sampling, they are more convenient and reproducible for routine monitoring. Also, combining blood NfL with neuroimaging techniques like MRI can improve the detection and management of central nervous system disorders.