To determine if t-Tau, NF-L, GFAP and UCH-L1 protein biomarkers are elevated in early time points of acute concussion/mild traumatic brain injury patient serum and saliva, relative to control samples.

t-Tau, NF-L, GFAP and UCH-L1 levels have been reported to increase in cerebral spinal fluid (CSF) and blood following head trauma within 24 hours or longer, and are candidate diagnostic and prognostic biomarkers of concussion and mild to moderate TBI. However, limited information exists on the relationship between these biomarkers at short time points post-injury, and detectability in saliva of mTBI patients.

Biomarker analysis of serum from a total of 120 participants, derived from two independent sample groups consisting of 60 concussion/mTBI patients each, with blood collected within 1-4 hr and 8-16 hr post-injury, respectively, was compared with 30 healthy control sera. Saliva samples were collected after 8-16 hr post-injury from a n= 30 subset of the same patients. Quanterix Simoa 4-plex immunoassay was used for highly sensitive measurements of these biomarkers.

Median levels of NF-L, GFAP and UCH-L1 were significantly higher in independent sets of patient serum samples (n= 60 each), both at early (1-4 hr) and later (8-16 hr) time points post-mTBI/concussion, relative to control samples (n = 30) (p < 0.0001,  = 0.0001, <0.0001, respectively).  Low levels of t-Tau are detected, but are significantly elevated post-concussion relative to controls (p= 0.0001). Significant correlations were observed between levels of t-Tau and UCH-L1,  NF-L and GFAP, and t-Tau and GFAP  in both post-injury time-point groups, and between NF-L and UCH-L1 levels in the 8-16 hr group. The four biomarkers were detected in saliva from concussion/mTBI patients (n=30). 

This study supports the utility of ultra-sensitive multiplex immunoassays to detect increases in CNS proteins at high sensitivity in serum and saliva within 1-4 and 8-16 hr of concussion/mTBI.