Browsing by Subject "Brain concussion"
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Item Age of First Concussion and Cognitive, Psychological, and Physical Outcomes in NCAA Collegiate Student Athletes(Springer, 2022) Moody, Jena N.; Hayes, Jasmeet P.; Buckley, Thomas A.; Schmidt, Julianne D.; Broglio, Steven P.; McAllister, Thomas W.; McCrea, Michael; Pasquina, Paul F.; Caccese, Jaclyn B.; Psychiatry, School of MedicineObjective: Concussions are common among youth athletes and could disrupt critical neurodevelopment. This study examined the association between age of first concussion (AFC) and neurocognitive performance, psychological distress, postural stability, and symptoms commonly associated with concussion in healthy collegiate men and women student athletes. Methods: Participants included 4267 collegiate athletes from various contact, limited-contact, and non-contact sports (1818 women and 2449 men) who completed baseline assessments as part of the Concussion Assessment, Research and Education (CARE) Consortium. Psychological distress was assessed with the Brief Symptom Inventory 18; neurocognitive performance was assessed with the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT); symptoms commonly associated with concussion were assessed with the ImPACT Post-Concussion Symptom Scale; postural stability was assessed with the Balance Error Scoring System. Generalized linear models were used to examine the effects of AFC on clinical outcomes separately in men and women. Results: Later AFC was associated with lower global (Exp(B) = 0.96, P = 0.001) and somatic (Exp(B) = 0.96, P = 0.002) psychological distress on the Brief Symptom Inventory 18 and faster ImPACT reaction time (B = - 0.003, P = 0.001) in women. AFC was not associated with any clinical outcomes in men. Conclusion: Younger AFC was associated with some differences in psychological distress and reaction time among women but not men; however, these results are likely not clinically meaningful. Sociodemographic disparities, pre-existing conditions, and sport type may impact clinical and cognitive outcomes in collegiate athletes more than concussion history. Future work should examine the relationship between AFC and lifespan-related outcomes.Item Assessment of Blood Biomarker Profile After Acute Concussion During Combative Training Among US Military Cadets(JAMA, 2021-02) Giza, Christopher C.; McCrea, Michael; Huber, Daniel; Cameron, Kenneth L.; Houston, Megan N.; Jackson, Jonathan C.; McGinty, Gerald; Pasquina, Paul; Broglio, Steven P.; Brooks, Alison; DiFiori, John; Duma, Stefan; Harezlak, Jaroslaw; Goldman, Joshua; Guskiewicz, Kevin; McAllister, Thomas W.; McArthur, David; Meier, Timothy B.; Mihalik, Jason P.; Nelson, Lindsay D.; Rowson, Steven; Gill, Jessica; Foroud, Tatiana; Katz, Barry; Saykin, Andrew; Campbell, Darren E.; Svoboda, Steven; Psychiatry, School of MedicineImportance: Validation of protein biomarkers for concussion diagnosis and management in military combative training is important, as these injuries occur outside of traditional health care settings and are generally difficult to diagnose. Objective: To investigate acute blood protein levels in military cadets after combative training-associated concussions. Design, setting, and participants: This multicenter prospective case-control study was part of a larger cohort study conducted by the National Collegiate Athletic Association and the US Department of Defense Concussion Assessment Research and Education (CARE) Consortium from February 20, 2015, to May 31, 2018. The study was performed among cadets from 2 CARE Consortium Advanced Research Core sites: the US Military Academy at West Point and the US Air Force Academy. Cadets who incurred concussions during combative training (concussion group) were compared with cadets who participated in the same combative training exercises but did not incur concussions (contact-control group). Clinical measures and blood sample collection occurred at baseline, the acute postinjury point (<6 hours), the 24- to 48-hour postinjury point, the asymptomatic postinjury point (defined as the point at which the cadet reported being asymptomatic and began the return-to-activity protocol), and 7 days after return to activity. Biomarker levels and estimated mean differences in biomarker levels were natural log (ln) transformed to decrease the skewness of their distributions. Data were collected from August 1, 2016, to May 31, 2018, and analyses were conducted from March 1, 2019, to January 14, 2020. Exposure: Concussion incurred during combative training. Main outcomes and measures: Proteins examined included glial fibrillary acidic protein, ubiquitin C-terminal hydrolase-L1, neurofilament light chain, and tau. Quantification was conducted using a multiplex assay (Simoa; Quanterix Corp). Clinical measures included the Sport Concussion Assessment Tool-Third Edition symptom severity evaluation, the Standardized Assessment of Concussion, the Balance Error Scoring System, and the 18-item Brief Symptom Inventory. Results: Among 103 military service academy cadets, 67 cadets incurred concussions during combative training, and 36 matched cadets who engaged in the same training exercises did not incur concussions. The mean (SD) age of cadets in the concussion group was 18.6 (1.3) years, and 40 cadets (59.7%) were male. The mean (SD) age of matched cadets in the contact-control group was 19.5 (1.3) years, and 25 cadets (69.4%) were male. Compared with cadets in the contact-control group, those in the concussion group had significant increases in glial fibrillary acidic protein (mean difference in ln values, 0.34; 95% CI, 0.18-0.50; P < .001) and ubiquitin C-terminal hydrolase-L1 (mean difference in ln values, 0.97; 95% CI, 0.44-1.50; P < .001) levels at the acute postinjury point. The glial fibrillary acidic protein level remained high in the concussion group compared with the contact-control group at the 24- to 48-hour postinjury point (mean difference in ln values, 0.22; 95% CI, 0.06-0.38; P = .007) and the asymptomatic postinjury point (mean difference in ln values, 0.21; 95% CI, 0.05-0.36; P = .01). The area under the curve for all biomarkers combined, which was used to differentiate cadets in the concussion and contact-control groups, was 0.80 (95% CI, 0.68-0.93; P < .001) at the acute postinjury point. Conclusions and relevance: This study's findings indicate that blood biomarkers have potential for use as research tools to better understand the pathobiological changes associated with concussion and to assist with injury identification and recovery from combative training-associated concussions among military service academy cadets. These results extend the previous findings of studies of collegiate athletes with sport-associated concussions.Item Association of Alzheimer's Disease Polygenic Risk Score with Concussion Severity and Recovery Metrics(Springer, 2025) Dybing, Kaitlyn M.; McAllister, Thomas W.; Wu, Yu‑Chien; McDonald, Brenna C.; Broglio, Steven P.; Mihalik, Jason P.; Guskiewicz, Kevin M.; Goldman, Joshua T.; Jackson, Jonathan C.; Saykin, Andrew J.; Risacher, Shannon L.; Nudelman, Kelly N. H.; Radiology and Imaging Sciences, School of MedicineBackground: Identification of genetic alleles associated with both Alzheimer's disease (AD) and concussion severity/recovery could help explain the association between concussion and elevated dementia risk. However, there has been little investigation into whether AD risk genes associate with concussion severity/recovery, and the limited findings are mixed. Objective: We used AD polygenic risk scores (PRS) and APOE genotypes to investigate any such associations in the NCAA-DoD Grand Alliance CARE Consortium (CARE) dataset. Methods: We assessed six concussion outcomes in 931 participants, including two recovery measures (number of days to asymptomatic and to return to play (RTP)) and four severity measures (scores on SAC and BESS, SCAT symptom severity and total number of symptoms). We calculated the PRS using a published score and performed multiple linear regression to assess the relationship of the PRS with outcomes. We also used ANOVAs, t-tests, and chi-square tests to examine outcomes by APOE genotype. Results: Higher PRS was associated with longer injury to RTP time in the normal RTP (< 24 days) subgroup (p = 0.024). A one standard deviation increase in the PRS resulted in a 9.89 hour increase to RTP time. This result was no longer significant after inclusion of covariates. There were no other consistently significant effects. Conclusions: Our findings suggest high AD genetic risk is not associated with more severe concussions or poor recovery in young adults. Future studies should attempt to replicate these findings in larger samples with longer follow-up using PRS calculated from diverse populations.Item Association of Blood Biomarkers of Inflammation With Acute Concussion in Collegiate Athletes and Military Service Academy Cadets(Wolters Kluwer, 2024) Meier, Timothy B.; Huber, Daniel L.; Goeckner, Bryna D.; Gill, Jessica M.; Pasquina, Paul; Broglio, Steven P.; McAllister, Thomas W.; Harezlak, Jaroslaw; McCrea, Michael A.; CARE Consortium Investigators; Psychiatry, School of MedicineBackground and objectives: The objective was to characterize the acute effects of concussion (a subset of mild traumatic brain injury) on serum interleukin (IL)-6 and IL-1 receptor antagonist (RA) and 5 additional inflammatory markers in athletes and military service academy members from the Concussion Assessment, Research, and Education Consortium and to determine whether these markers aid in discrimination of concussed participants from controls. Methods: Athletes and cadets with concussion and matched controls provided blood at baseline and postinjury visits between January 2015 and March 2020. Linear models investigated changes in inflammatory markers measured using Meso Scale Discovery assays across time points (baseline and 0-12, 12-36, 36-60 hours). Subanalyses were conducted in participants split by sex and injury population. Logistic regression analyses tested whether acute levels of IL-6 and IL-1RA improved discrimination of concussed participants relative to brain injury markers (glial fibrillary acidic protein, tau, neurofilament light, ubiquitin c-terminal hydrolase-L1) or clinical data (Sport Concussion Assessment Tool-Third Edition, Standardized Assessment of Concussion, Balance Error Scoring System). Results: Participants with concussion (total, N = 422) had elevated IL-6 and IL-1RA at 0-12 hours vs controls (n = 345; IL-6: mean difference [MD] (standard error) = 0.701 (0.091), p < 0.0001; IL-1RA: MD = 0.283 (0.042), p < 0.0001) and relative to baseline (IL-6: MD = 0.656 (0.078), p < 0.0001; IL-1RA: MD = 0.242 (0.038), p < 0.0001), 12-36 hours (IL-6: MD = 0.609 (0.086), p < 0.0001; IL-1RA: MD = 0.322 (0.041), p < 0.0001), and 36-60 hours (IL-6: MD = 0.818 (0.084), p < 0.0001; IL-1RA: MD = 0.317 (0.040), p < 0.0001). IL-6 and IL-1RA were elevated in participants with sport (IL-6: MD = 0.748 (0.115), p < 0.0001; IL-1RA: MD = 0.304 (0.055), p < 0.0001) and combative-related concussions (IL-6: MD = 0.583 (0.178), p = 0.001; IL-1RA: MD = 0.312 (0.081), p = 0.0001). IL-6 was elevated in male (MD = 0.734 (0.105), p < 0.0001) and female participants (MD = 0.600 (0.177), p = 0.0008); IL-1RA was only elevated in male participants (MD = 0.356 (0.047), p < 0.0001). Logistic regression showed the inclusion of IL-6 and IL-1RA at 0-12 hours improved the discrimination of participants with concussion from controls relative to brain injury markers (χ2(2) = 17.855, p = 0.0001; area under the receiver operating characteristic curve [AUC] 0.73 [0.66-0.80] to 0.78 [0.71-0.84]), objective clinical measures (balance and cognition; χ2(2) = 40.661, p < 0.0001; AUC 0.81 [0.76-0.86] to 0.87 [0.83-0.91]), and objective and subjective measures combined (χ2(2) = 13.456, p = 0.001; AUC 0.97 [0.95-0.99] to 0.98 [0.96-0.99]), although improvement in AUC was only significantly relative to objective clinical measures. Discussion: IL-6 and IL-1RA (male participants only) are elevated in the early-acute window postconcussion and may aid in diagnostic decisions beyond traditional blood markers and common clinical measures. IL-1RA results highlight sex differences in the immune response to concussion which should be considered in future biomarker work.Item Characteristics and Outcomes of Athletes With Slow Recovery From Sports-Related Concussion: A CARE Consortium Study(Wolters Kluwer, 2023) McAllister, Thomas W.; Broglio, Steven P.; Katz, Barry P.; Perkins, Susan M.; LaPradd, Michelle; Zhou, Wenxian; McCrea, Michael A.; Concussion Assessment, Research and Education (CARE) Consortium; Psychiatry, School of MedicineBackground and objectives: Some athletes experience a slow recovery after sport-related concussion (SRC). There is little agreement on what constitutes slow recovery, however, and minimal data on the prevalence, predictors, or prognosis for this group. The objectives of this study were to apply an operationalized definition of slow recovery and characterize predictors and long-term prognosis of these individuals. Methods: This is a prospective multisite observational study of collegiate athletes. Participants underwent multimodal assessments preseason and 5 additional time points after SRC. Time from injury to initiation of return to play progression (asymptomatic timepoint) and from injury to return to play (RTP) were the primary markers of recovery. Results: One thousand seven hundred fifty-one concussed male and female collegiate athletes were studied. Eighty percent of participants reached the asymptomatic and/or RTP time points by days 14 and 24, respectively. Slow recovery was thus defined as exceeding 1 or both of those intervals (n = 399). This group was statistically more likely to be female (41.1% vs 35.6%, p = 0.05), have higher initial postinjury SCAT symptom severity scores (mean [SD]: 36.6 [23.4] vs 25.4 [19.9], p < 0.001), lower postinjury Standardized Assessment of Concussion scores (mean [SD]:25.74 [2.98] vs 26.26 [2.85], p = 0.004), perform worse on the postinjury Balance Error Scoring System (mean [SD]: 17.8 [8.9] vs 15.9 [8.5], p < 0.01), have fewer assessments in the first 14 days after injury (mean [SD]: 48.8 [29.7] vs 67.9 [24.6], p < 0.01), and be injured in practice (70.7% vs 65.1%, p = 0.04). 77.6% of the slow recovery group returned to play within 60 days of injury, and 83.4% (n = 349) returned to play within 90 days of injury. Only 10.6% had not returned to play 6 months postinjury. Discussion: This study suggests an overall favorable prognosis for slowly recovering athletes and provides data for athletes and medical teams to consider in calibrating RTP expectations and making decisions about medical disqualification vs ongoing engagement in their sport.Item Estimated age of first exposure to American football and outcome from concussion(Wolters Kluwer, 2020-11-24) Caccese, Jaclyn B.; Houck, Zac; Kaminski, Thomas W.; Clugston, James R.; Iverson, Grant L.; Bryk, Kelsey N.; Oldham, Jessie R.; Pasquina, Paul F.; Broglio, Steven P.; McAllister, Thomas W.; McCrea, Michael; Reed Hoy, April Marie; Hazzard, Joseph B., Jr.; Kelly, Louise A.; Ortega, Justus D.; Port, Nicholas; Putukian, Margot; Langford, T. Dianne; Giza, Christopher C.; Goldman, Joshua T.; Benjamin, Holly J.; Schmidt, Julianne D.; Feigenbaum, Luis A.; Eckner, James T.; Mihalik, Jason P.; Dysart Miles, Jessica; Anderson, Scott; Master, Christina L.; Collins, Micky W.; Kontos, Anthony P.; Chrisman, Sara P.D.; Brooks, Alison; Jackson, Jonathan C.; McGinty, Gerald; Cameron, Kenneth L.; Susmarski, Adam; O'Donnell, Patrick G.; Duma, Stefan; Rowson, Steve; Miles, Christopher M.; Bullers, Christopher T.; Dykhuizen, Brian H.; Lintner, Laura; Buckley, Thomas A.; Psychiatry, School of MedicineObjective: To examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion. Methods: Participants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)-Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24-48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data. Participants sustained a medically diagnosed concussion between baseline testing and postconcussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Balance Error Scoring System (BESS) total score, and Brief Symptom Inventory 18 (BSI-18) subscores. The eAFE was defined as participant's age at the time of assessment minus self-reported number of years playing football. Results: In unadjusted regression models, younger eAFE was associated with lower (worse) ImPACT Visual Motor Speed (R 2 = 0.031, p = 0.012) at 24-48 hours following injury and lower (better) BSI-18 Somatization subscores (R 2 = 0.014, p = 0.038) when the athletes were asymptomatic. The effect sizes were very small. The eAFE was not associated with the number of days until asymptomatic, other ImPACT composite scores, BESS total score, or other BSI-18 subscores. Conclusion: Earlier eAFE to American football was not associated with longer symptom recovery, worse balance, worse cognitive performance, or greater psychological distress following concussion. In these NCAA football players, longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion.Item Investigating omega-3 fatty acids' neuroprotective effects in repetitive subconcussive neural injury: Study protocol for a randomized placebo-controlled trial(Public Library of Science, 2025-04-24) Beauregard, Lauren H.; Bazarian, Jeffrey J.; Johnson, Blair D.; Cheng, Hu; Ellis, Gage; Kronenberger, William; Calder, Philip C.; Chen, Zhongxue; Silveyra, Patricia; Quinn, Patrick D.; Newman, Sharlene D.; Mickleborough, Timothy D.; Kawata, Keisuke; Psychiatry, School of MedicineSoccer (football) is the most popular sport globally, with 265 million players across all ages and sexes. Repetitive subconcussive head impacts due to heading of the soccer ball can pose threats to healthy brain development and aging. Omega-3 fatty acids, especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), may have neuroprotective effects, but it remains unclear what aspects of neural health benefit from DHA+EPA when faced with subconcussive head impacts. In a randomized placebo-controlled trial, 208 soccer players will complete baseline measures including demographics, blood sampling, dietary recalls, and psychological assessment. Participants will be randomly assigned to ingest DHA+EPA [3.4g/d: DHA 2.4g+EPA 1.0g] or placebo daily for 8 weeks followed by a subconcussion intervention phase. During the subconcussion intervention, participants will perform a session of 20 controlled soccer headings, with a second session 24 hours later. Blood samples, neuroimaging data, autonomic reactivity, and clinical measures (symptoms, oculomotor, cognition) will be collected pre-heading and 24-hour post-1st session, 24-hour post-2nd session, and 7-day post-2nd session. The primary hypothesis is that DHA+EPA pretreatment will promote neuronal and astrocyte resiliency to subconcussive head impacts, as assessed by blood biomarkers of brain injury, axonal microstructure measured by diffusion tensor imaging, and whole-brain resting-state connectivity. It is proposed that pretreatment will preserve autonomic function, as assessed by the cold pressor test (CPT), as well as oculomotor and cognitive function, even after head impacts. Data from this trial will help clarify the combined effect of DHA+EPA on brain molecular, cellular, and physiological health in response to subconcussive head impacts. If the hypotheses are confirmed, the findings will support a highly practical intervention for mitigating the neurodegenerative cascade triggered by head impacts.Item Longitudinal Associations Between Blood Biomarkers and White Matter MRI in Sport-Related Concussion(Wolters Kluwer, 2023) Wu, Yu-Chien; Wen, Qiuting; Thukral, Rhea; Yang, Ho-Ching; Gill, Jessica M.; Gao, Sujuan; Lane, Kathleen A.; Meier, Timothy B.; Riggen, Larry D.; Harezlak, Jaroslaw; Giza, Christopher C.; Goldman, Joshua; Guskiewicz, Kevin M.; Mihalik, Jason P.; LaConte, Stephen M.; Duma, Stefan M.; Broglio, Steven P.; Saykin, Andrew J.; Walker McAllister, Thomas; McCrea, Michael A.; Radiology and Imaging Sciences, School of MedicineBackground and objectives: To study longitudinal associations between blood-based neural biomarkers (including total tau, neurofilament light [NfL], glial fibrillary acidic protein [GFAP], and ubiquitin C-terminal hydrolase-L1) and white matter neuroimaging biomarkers in collegiate athletes with sport-related concussion (SRC) from 24 hours postinjury to 1 week after return to play. Methods: We analyzed clinical and imaging data of concussed collegiate athletes in the Concussion Assessment, Research, and Education (CARE) Consortium. The CARE participants completed same-day clinical assessments, blood draws, and diffusion tensor imaging (DTI) at 3 time points: 24-48 hours postinjury, point of becoming asymptomatic, and 7 days after return to play. DTI probabilistic tractography was performed for each participant at each time point to render 27 participant-specific major white matter tracts. The microstructural organization of these tracts was characterized by 4 DTI metrics. Mixed-effects models with random intercepts were applied to test whether white matter microstructural abnormalities are associated with the blood-based biomarkers at the same time point. An interaction model was used to test whether the association varies across time points. A lagged model was used to test whether early blood-based biomarkers predict later microstructural changes. Results: Data from 77 collegiate athletes were included in the following analyses. Among the 4 blood-based biomarkers, total tau had significant associations with the DTI metrics across the 3 time points. In particular, high tau level was associated with high radial diffusivity (RD) in the right corticospinal tract (β = 0.25, SE = 0.07, p FDR-adjusted = 0.016) and superior thalamic radiation (β = 0.21, SE = 0.07, p FDR-adjusted = 0.042). NfL and GFAP had time-dependent associations with the DTI metrics. NfL showed significant associations only at the asymptomatic time point (|β|s > 0.12, SEs <0.09, psFDR-adjusted < 0.05) and GFAP showed a significant association only at 7 days after return to play (βs > 0.14, SEs <0.06, psFDR-adjusted < 0.05). The p values for the associations of early tau and later RD were not significant after multiple comparison adjustment, but were less than 0.1 in 7 white matter tracts. Discussion: This prospective study using data from the CARE Consortium demonstrated that in the early phase of SRC, white matter microstructural integrity detected by DTI neuroimaging was associated with elevated levels of blood-based biomarkers of traumatic brain injury. Total tau in the blood showed the strongest association with white matter microstructural changes.Item Opportunities for Prevention of Concussion and Repetitive Head Impact Exposure in College Football Players: A Concussion Assessment, Research, and Education (CARE) Consortium Study(American Medical Association, 2021) McCrea, Michael A.; Shah, Alok; Duma, Stefan; Rowson, Steven; Harezlak, Jaroslaw; McAllister, Thomas W.; Broglio, Steven P.; Giza, Christopher C.; Goldman, Joshua; Cameron, Kenneth L.; Houston, Megan N.; McGinty, Gerald; Jackson, Jonathan C.; Guskiewicz, Kevin; Mihalik, Jason P.; Brooks, M. Alison; Pasquina, Paul; Stemper, Brian D.; Psychiatry, School of MedicineImportance: Concussion ranks among the most common injuries in football. Beyond the risks of concussion are growing concerns that repetitive head impact exposure (HIE) may increase risk for long-term neurologic health problems in football players. Objective: To investigate the pattern of concussion incidence and HIE across the football season in collegiate football players. Design, setting, and participants: In this observational cohort study conducted from 2015 to 2019 across 6 Division I National Collegiate Athletic Association (NCAA) football programs participating in the Concussion Assessment, Research, and Education (CARE) Consortium, a total of 658 collegiate football players were instrumented with the Head Impact Telemetry (HIT) System (46.5% of 1416 eligible football players enrolled in the CARE Advanced Research Core). Players were prioritized for instrumentation with the HIT System based on their level of participation (ie, starters prioritized over reserves). Exposure: Participation in collegiate football games and practices from 2015 to 2019. Main outcomes and measures: Incidence of diagnosed concussion and HIE from the HIT System. Results: Across 5 seasons, 528 684 head impacts recorded from 658 players (all male, mean age [SD], 19.02 [1.25] years) instrumented with the HIT System during football practices or games met quality standards for analysis. Players sustained a median of 415 (interquartile range [IQR], 190-727) recorded head impacts (ie, impacts) per season. Sixty-eight players sustained a diagnosed concussion. In total, 48.5% of concussions (n = 33) occurred during preseason training, despite preseason representing only 20.8% of the football season (0.059 preseason vs 0.016 regular-season concussions per team per day; mean difference, 0.042; 95% CI, 0.020-0.060; P = .001). Total HIE in the preseason occurred at twice the proportion of the regular season (324.9 vs 162.4 impacts per team per day; mean difference, 162.6; 95% CI, 110.9-214.3; P < .001). Every season, HIE per athlete was highest in August (preseason) (median, 146.0 impacts; IQR, 63.0-247.8) and lowest in November (median, 80.0 impacts; IQR, 35.0-148.0). Over 5 seasons, 72% of concussions (n = 49) (game proportion, 0.28; 95% CI, 0.18-0.40; P < .001) and 66.9% of HIE (262.4 practices vs 137.2 games impacts per player; mean difference, 125.3; 95% CI, 110.0-140.6; P < .001) occurred in practice. Even within the regular season, total HIE in practices (median, 175.0 impacts per player per season; IQR, 76.0-340.5) was 84.2% higher than in games (median, 95.0 impacts per player per season; IQR, 32.0-206.0). Conclusions and relevance: Concussion incidence and HIE among college football players are disproportionately higher in the preseason than regular season, and most concussions and HIE occur during football practices, not games. These data point to a powerful opportunity for policy, education, and other prevention strategies to make the greatest overall reduction in concussion incidence and HIE in college football, particularly during preseason training and football practices throughout the season, without major modification to game play. Strategies to prevent concussion and HIE have important implications to protecting the safety and health of football players at all competitive levels.Item Pathological Computed Tomography Features Associated With Adverse Outcomes After Mild Traumatic Brain Injury(American Medical Association, 2021) Yuh, Esther L.; Jain, Sonia; Sun, Xiaoying; Pisică, Dana; Harris, Mark H.; Taylor, Sabrina R.; Markowitz, Amy J.; Mukherjee, Pratik; Verheyden, Jan; Giacino, Joseph T.; Levin, Harvey S.; McCrea, Michael; Stein, Murray B.; Temkin, Nancy R.; Diaz-Arrastia, Ramon; Robertson, Claudia S.; Lingsma, Hester F.; Okonkwo, David O.; Maas, Andrew I. R.; Manley, Geoffrey T.; TRACK-TBI Investigators for the CENTER-TBI Investigators; Adeoye, Opeolu; Badjatia, Neeraj; Boase, Kim; Bodien, Yelena; Corrigan, John D.; Crawford, Karen; Dikmen, Sureyya; Duhaime, Ann-Christine; Ellenbogen, Richard; Feeser, V. Ramana; Ferguson, Adam R.; Foreman, Brandon; Gardner, Raquel; Gaudette, Etienne; Gonzalez, Luis; Gopinath, Shankar; Gullapalli, Rao; Hemphill, J. Claude; Hotz, Gillian; Keene, C. Dirk; Kramer, Joel; Kreitzer, Natalie; Lindsell, Chris; Machamer, Joan; Madden, Christopher; Martin, Alastair; McAllister, Thomas; Merchant, Randall; Nelson, Lindsay; Ngwenya, Laura B.; Noel, Florence; Nolan, Amber; Palacios, Eva; Perl, Daniel; Rabinowitz, Miri; Rosand, Jonathan; Sander, Angelle; Satris, Gabriella; Schnyer, David; Seabury, Seth; Toga, Arthur; Valadka, Alex; Vassar, Mary; Zafonte, Ross; Psychiatry, School of MedicineImportance: A head computed tomography (CT) with positive results for acute intracranial hemorrhage is the gold-standard diagnostic biomarker for acute traumatic brain injury (TBI). In moderate to severe TBI (Glasgow Coma Scale [GCS] scores 3-12), some CT features have been shown to be associated with outcomes. In mild TBI (mTBI; GCS scores 13-15), distribution and co-occurrence of pathological CT features and their prognostic importance are not well understood. Objective: To identify pathological CT features associated with adverse outcomes after mTBI. Design, setting, and participants: The longitudinal, observational Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study enrolled patients with TBI, including those 17 years and older with GCS scores of 13 to 15 who presented to emergency departments at 18 US level 1 trauma centers between February 26, 2014, and August 8, 2018, and underwent head CT imaging within 24 hours of TBI. Evaluations of CT imaging used TBI Common Data Elements. Glasgow Outcome Scale-Extended (GOSE) scores were assessed at 2 weeks and 3, 6, and 12 months postinjury. External validation of results was performed via the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. Data analyses were completed from February 2020 to February 2021. Exposures: Acute nonpenetrating head trauma. Main outcomes and measures: Frequency, co-occurrence, and clustering of CT features; incomplete recovery (GOSE scores <8 vs 8); and an unfavorable outcome (GOSE scores <5 vs ≥5) at 2 weeks and 3, 6, and 12 months. Results: In 1935 patients with mTBI (mean [SD] age, 41.5 [17.6] years; 1286 men [66.5%]) in the TRACK-TBI cohort and 2594 patients with mTBI (mean [SD] age, 51.8 [20.3] years; 1658 men [63.9%]) in an external validation cohort, hierarchical cluster analysis identified 3 major clusters of CT features: contusion, subarachnoid hemorrhage, and/or subdural hematoma; intraventricular and/or petechial hemorrhage; and epidural hematoma. Contusion, subarachnoid hemorrhage, and/or subdural hematoma features were associated with incomplete recovery (odds ratios [ORs] for GOSE scores <8 at 1 year: TRACK-TBI, 1.80 [95% CI, 1.39-2.33]; CENTER-TBI, 2.73 [95% CI, 2.18-3.41]) and greater degrees of unfavorable outcomes (ORs for GOSE scores <5 at 1 year: TRACK-TBI, 3.23 [95% CI, 1.59-6.58]; CENTER-TBI, 1.68 [95% CI, 1.13-2.49]) out to 12 months after injury, but epidural hematoma was not. Intraventricular and/or petechial hemorrhage was associated with greater degrees of unfavorable outcomes up to 12 months after injury (eg, OR for GOSE scores <5 at 1 year in TRACK-TBI: 3.47 [95% CI, 1.66-7.26]). Some CT features were more strongly associated with outcomes than previously validated variables (eg, ORs for GOSE scores <5 at 1 year in TRACK-TBI: neuropsychiatric history, 1.43 [95% CI .98-2.10] vs contusion, subarachnoid hemorrhage, and/or subdural hematoma, 3.23 [95% CI 1.59-6.58]). Findings were externally validated in 2594 patients with mTBI enrolled in the CENTER-TBI study. Conclusions and relevance: In this study, pathological CT features carried different prognostic implications after mTBI to 1 year postinjury. Some patterns of injury were associated with worse outcomes than others. These results support that patients with mTBI and these CT features need TBI-specific education and systematic follow-up.