New potential blood biomarker for brain injury

By Mardi Chapman

17 Jul 2020

Serum levels of the neurofilament light chain (NfL) may be a useful biomarker of neuroaxonal injury in people with traumatic brain injuries (TBI), new research suggests.

Already validated in neurodegenerative disorders such as Alzheimer’s disease and MS, NfL was recently measured in a cohort of Swedish ice-hockey players and in a US clinic-based TBI cohort.

The study, published in Neurology, first demonstrated that paired serum NfL and CSF NfL were closely correlated in both athletes with post-concussive symptoms (PCS) and healthy controls.

It also found that NfL concentrations were similar in hockey players during the preseason and in healthy controls but increased in players with PCS.

Serum NfL concentrations could also predict the duration of symptoms or return to play after the concussion.

NfL levels at 6-days post acute concussion were 1.3 times higher in players with a return to play time longer than 10 days compared to those who returned to play in 10 days or less.

As well, NfL levels were twice as high in players with PCS longer than one year compared to PCS up to one year.

The study found NfL levels also increased over months and years in all but one player from a small subset of players with persistent PCS who agreed to longitudinal assessments.

Both CSF and serum NfL showed associations with the number of concussions in players.

In the clinic-based cohort of patients with either mild, moderate or severe TBI, NfL concentrations were about double that of healthy controls.

While the NfL concentrations decreased over the course of five years from injury, they remained significantly elevated compared to controls for a prolonged period.

Serum NfL was able to distinguish mild, moderate and severe TBI cases from controls at 30 days and moderate or severe TBI from controls at 90 days.

Increased serum NfL concentrations were associated with worse Glasgow Outcome Scale-Extended (GOS-E) scores, and decreases in brain MRI volumes, DTI measures of white matter axonal integrity and DTI corpus callosum changes.

“Our findings suggest that NfL concentrations in serum offer rapid and accessible means of assessing and predicting neuronal damage in patients with TBI,” the study authors said.

The findings are consistent with experimental and post-mortem studies that suggest exposure to repetitive head trauma may cause chronic axonal degeneration.

In particular, “the strong relationships seen between serum NfL and DTI measures of traumatic axonal injury (TAI) suggest that serum NfL could be used to assess TAI or as a prognostic blood biomarker of disease progression or neuroaxonal damage following TBI,” they wrote.

“In light of these findings, serum NfL may have a potential role in facilitating development of novel disease-modifying therapeutics, and possibly guiding treatment decisions,” they concluded.

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