No change in plasma tau and serum neurofilament light concentrations in adolescent athletes following sport-related concussion

Abstract

Sport-related concussion (SRC), a mild form of traumatic brain injury (TBI), is a common injury in contact sports. Health care professionals rely on subjective criteria (e.g., symptoms), as there is no objective marker for identification of athletes with SRC. Blood-based biomarkers have shown promise as diagnostic and prognostic tools following TBI and SRC. In the present study, we examined plasma tau and serum NF-L, two biomarkers for neuronal/axonal injury, concentrations at preseason and following SRC in contact sport athletes (n = 11) using ultrasensitive single molecule array (Simoa) assays. Preseason baseline samples were collected, and post-concussion samples were obtained at 6- and 14-days following injury. We found no difference between baseline, 6-day and 14-day post-concussion concentrations of tau (p = 0.14) or NF-L (p = 0.53). Further, no difference was found between preseason baseline and all post-SRC samples for tau (p = 0.22) or NF-L (p = 0.98). The total number of symptoms reported on the Standardized Assessment of Concussion- 3rd Edition (SCAT3) and associated symptom severity scores increased from preseason to 6-days post-SRC but returned to baseline values at 14-days (p = 0.02 and p = 0.003, respectively). These results suggest that the severity of neuronal injury in this cohort of contact sport athletes with clinical uncomplicated SRC was too low to be detected by tau and NF-L measurements in blood samples obtained at 6- and 14-days post-injury.

Fig 1. Tau and NF-L concentrations do not change following uncomplicated SRC.

(A) Tau concentrations at baseline, and at 6- and 14-days following uncomplicated SRC. (B) NF-L concentrations at baseline, and at 6- and 14-days following uncomplicated SRC.

Fig 2. Tau and NF-L concentrations at preseason and following uncomplicated SRC (all time points).

(A) Tau concentrations were unchanged in post-concussion samples (all times) compared to preseason samples. (B) There was no difference between preseason and post-concussion (all times) NF-L concentrations.

Fig 3. Total number of symptoms and symptom severity scores assessed by SCAT3 at preseason and following uncomplicated SRC.

(A) The total number of symptoms reported on the SCAT3 increased from preseason to 6-days following uncomplicated SRC and returned to baseline at 14-days. Maximum possible number of symptoms is 22. (B) Symptom severity scores increased at 6-days following uncomplicated SRC compared to baseline and returned to baseline at 14-days following injury. Maximum possible symptom severity score is 132.

Fig 4. Total number of errors on the balance error scoring system (BESS) at preseason, and 6- and 14-days following uncomplicated SRC.

The total number of errors assessed by the BESS was unchanged following uncomplicated SRC compared to preseason values. The BESS is calculated by adding one point per error during 3 separate 20-second tests.

Fig 5. Total number of correct answers on the standardized assessment of concussion (SAC) at preseason, and 6- and 14-days following uncomplicated SRC.

Total number of correct answers, out of 31, was unchanged following uncomplicated SRC compared to preseason values.