Can a blood test reveal brain diseases years before symptoms appear? Neurosurgeon Dr. Jay Jagannathan recently posed this question on Instagram. He pointed to the Neurofilament Light Chain (NfL) test as a potential game-changer in brain health monitoring.
Why NfL Matters
Dr. Jagannathan explained that NfL is a protein released when nerve cells are damaged. Under normal conditions, these proteins stay inside neurons. However, when neurons are injured, fragments leak into the blood and spinal fluid. Elevated NfL levels are linked to conditions such as Alzheimer’s, Parkinson’s, multiple sclerosis, stroke, and traumatic brain injury.
Importantly, he noted: “You may feel fine, but NfL could already be sounding the alarm. Since nerve cells don’t repair easily, elevated levels indicate ongoing but silent brain damage — often years before symptoms appear.”
How the Test Works
As reported by the Indian Express, the NfL test is a simple blood draw. Using high-sensitivity platforms, doctors can measure these protein fragments with precision. According to Dr. Jagannathan, physicians may use NfL levels to flag early risks, track disease progression, or even monitor treatment response — sometimes before MRI scans show changes.
Prevention Still Comes First
Alongside testing, Dr. Jagannathan emphasized preventive lifestyle measures. He urged people to control blood pressure and blood sugar, sleep 7–8 hours, exercise regularly, follow a Mediterranean-style diet, avoid smoking and excess alcohol, and manage stress effectively. His reminder was clear: “Brain damage is often silent — until it isn’t. Don’t wait for symptoms. Ask your doctor about NfL testing if you’re at risk.”
Expert Opinion: How Reliable Is It?
Dr. Jagdish Chattnalli, senior minimally invasive brain and spine surgeon at HCG Hospitals Bengaluru, confirmed that NfL is one of the most sensitive blood markers of ongoing neuronal injury. Higher levels often predict faster decline or a higher chance of developing symptomatic diseases like Parkinson’s or Alzheimer’s.
The Limitations of NfL
However, Dr. Chattnalli cautioned that NfL is not disease-specific. A raised value signals neuronal damage but does not reveal the exact cause. He stressed that the test is most effective when combined with clinical evaluation, imaging, and other biomarkers.
Availability and Who Should Take It
Modern laboratories and reference centers now offer NfL testing, and validated assays are available globally. Still, routine population screening is not recommended. Instead, experts advise testing for:
- Individuals with concerning symptoms
- Patients with findings on imaging or neurological exams
- People with a strong family history or clear risk factors
Dr. Chattnalli summarized: “The best use of NfL is as part of a broader assessment, where knowing the trajectory of neuronal injury can meaningfully guide treatment.”