Q&A with Dr Marzena Fabis-Pedrini: Understanding neurofilament testing in MS

Neurofilament is a protein that helps support nerve fibres, keeping them strong and functioning well. In MS, these nerve fibres can become damaged. When that happens, a component of neurofilament called neurofilament light chain (NfL) is released into the spinal fluid and blood. What makes this so important is that the more damage occurs, the higher the NfL levels can be detected.

As modern tests are able to measure NfL from a simple blood sample, it offers a minimally invasive way to track the activity of the disease, predict future changes, and see how well treatments are working. NfL tends to increase during periods of active damage and decrease when treatment is effective, making it a strong candidate for personalised MS care

MRI scans and clinical checkups are crucial, as they provide snapshots in time, but they may not always catch early or subtle changes. NfL testing adds another layer by detecting signs of nerve fibre injury before new MRI lesions or symptoms appear. 

Rising NfL levels have been linked with a higher chance of relapses, new MRI activity and long-term disability. Because it is simple, repeatable, and relatively affordable, NfL testing gives clinicians a more dynamic view of what’s happening and enhances what we learn from MRI and clinical assessments.

NfL is unique because it directly reflects nerve fibre damage and can be measured easily through blood tests. Earlier biomarkers were often less specific, less sensitive, or required invasive procedures like spinal fluid sampling. This makes NfL a more practical and responsive biomarker for understanding near real-time disease activity and treatment response

We’re getting very close. Testing methods are becoming more standardised, and guidelines for interpreting results are being developed. There is strong evidence that NfL is a reliable marker for nerve damage, prognosis and treatment monitoring.

Some work is still needed. For example, determining ageadjusted reference ranges, but ongoing improvements and growing clinical confidence mean NfL is steadily moving from research settings into routine practice.

Together with Professors Allan Kermode and Bill Carroll, I’m researching longitudinal blood samples from people at all stages of MS and comparing their NfL levels with MRI results. One key question is whether rising NfL can act as an early warning sign for relapse before new MRI lesions appear.

The goal is to better understand how NfL can guide more precise monitoring and treatment decisions. This project was almost fully funded by MSWA, and we are truly grateful for this support.

Neurofilament testing could offer people with MS clearer and earlier insight into their disease. Because NfL can rise months or even years before symptoms or MRI changes, it may act as an early signal that treatment or monitoring needs to be adjusted. This supports more personalised, proactive care.

You can contribute by taking part in studies that collect blood samples for NfL testing. These samples are essential for improving the accuracy of reference levels and helping bring NfL testing into routine clinical use.