Subconcussive Impact-Dependent Increase in Plasma S100β Levels in Collegiate Football Players

Abstract

The current study investigates whether repetitive subconcussive impacts cause changes in plasma S100β levels, and also tests the associations between S100β changes and frequency/magnitude of impacts sustained. This prospective study of 22 Division-I collegiate football players included baseline and pre-season practices (one helmet-only and four full-gear). Blood samples were obtained and assessed for S100β levels at baseline and pre- to post-practices; symptom scores were assessed at each time-point. An accelerometer-embedded mouthguard was employed to measure the number of impacts (hits), peak linear acceleration (PLA), and peak rotational acceleration (PRA). Because we observed a distinct gap in impact exposure (hits, PLA, and PRA), players were clustered into lower (n = 7) or higher (n = 15) impact groups based on the sum of impact kinematics from all five practices. S100β levels significantly changed across the study duration. Although S100β levels remained stable from baseline to all pre-practice values, statistically significant acute increases in S100β levels were observed in all post-practice measures compared with the respective pre-practice values (range: 133-246% in the overall sample). Greater number of hits, sum of PLA, and sum of PRA were significantly associated with greater acute increases in S100β levels. There were significant differences in head impact kinematics between lower and higher impact groups (hits, 6 vs. 43 [M - M = 35, p < 0.001]; PLA, 99.4 vs. 1148.5 g [M - M = 1049.1, p < 0.001]; PRA, 7589 vs. 68,259 rad/s [M - M = 60,670, p < 0.001]). Players in the higher impact group showed consistently greater increases in plasma S100β levels, but not symptom scores, at each post-practice than the lower impact group. Collectively, these data suggest that although players continued to play without noticeable change in symptoms, a brain-enriched serological factor suggests an acute burden from head impacts. Assessing the effects of repetitive subconcussive head impacts on acute changes in S100β levels may be a clinically useful blood biomarker in tracking real-time acute brain damage in collegiate football players.

NFL blood levels are moderated by subconcussive impacts in a cohort of college football players

“…To track longitudinal changes in biomarkers indicative of repetitive brain injury from subconcussive blows, brain-derived blood-borne biomarkers are more practical than lumbar puncture for cerebrospinal fluid analyses. In a recent series of studies where blood was collected before and after repeated subconcussive head impacts sustained during college football summer training camp practices, we demonstrated that greater frequency and magnitude of subconcussive impacts were associated with greater increases in S100β plasma levels from pre-to post-impact time points (Kawata et al, 2017a). However, subconcussive head impact exposure was not associated with changes in plasma total Tau protein (Kawata et al, 2017b).…”

“…The Vector™ mouth guard (i1 Biometrics™, Inc., Kirkland, WA, USA) was used to measure the frequency (number of hits) and magnitude of head accelerations (peak linear and rotational accelerations) as previously described (Kawata et al, 2017a;Kawata et al, 2017b;Kawata et al, 2016b). After placing briefly in boiling water to soften the mold, mouth guards were molded to each participant's bite for a secure custom fit.…”

“…In a subset of collegiate football players from our previously published cohort studies (Kawata et al, 2017a;Kawata et al, 2017b;Kawata et al, 2016b), we assessed the effects of repeated subconcussive hits on changes in plasma NFL. We expected that the repetitive football subconcussive impacts would alter NFL levels particularly among players experiencing more frequent and higher magnitude impacts compared with players sustaining less frequent and lower magnitude impacts.…”

Response of protein S100B to playing American football, lifting weights, and treadmill running

“…Beginning in the 21st century, S100B has been under investigation as a serum biomarker of mild traumatic brain injury in sport, specifically as an indicator of sport‐related concussion and subconcussion injury . Although serum S100B concentration ([S100B]) has been shown to increase in response to the number of contacts an athlete experiences, [S100B] has also been shown to rise in relation to exercise alone .…”

“…[3][4][5][6][7][8][9][10][11][12] Beginning in the 21st century, S100B has been under investigation as a serum biomarker of mild traumatic brain injury in sport, specifically as an indicator of sport-related concussion and subconcussion injury. [13][14][15][16][17][18][19][20][21][22][23][24][25] Although serum S100B concentration ([S100B]) has been shown to increase in response to the number of contacts an athlete experiences, [16][17][18]21,25 [S100B] has also been shown to rise in relation to exercise alone. 16,[26][27][28] Findings of increased [S100B] caused by marathon running, 27 a 25-km running race, 16 jogging 10 km, 16 running for 40 minutes at ventilatory threshold, 28 sprinting for 2 minutes, 16 and a 7600 m swimming race, 26 paired with the presence of S100B in extracranial tissue, [29][30][31] have cast doubt over the use of S100B as a valid biomarker of brain injury in sport.…”