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Background: Concussion underreporting is endemic, and social norms are an established predictor of concussion reporting behavior. However, pluralistic ignorance--a situation in which most individuals in a group hold the belief that their peers' views differ from their own, despite views actually being similar--has not been studied in this context. Aim: To assess whether pluralistic ignorance contributes to concussion underreporting. Method: We surveyed 2,504 military service academy cadets. Each cadet was presented with a survey asking about their willingness to self-report a concussion, their perception of other cadets' willingness to report a concussion, and personal and demographic factors. Results. Most cadets viewed themselves as more willing to report a concussion than others (mean difference = 1.12, 95% CI [1.02, 1.21]), a belief consistent with pluralistic ignorance. Demographic characteristics were associated with holding this belief. For example, female cadets and upper-class cadets were more likely to show this disparity than male or under-class cadets, respectively. Collegiate athletes not only showed similar willingness to report concussion as nonathletes but also perceived other cadets as less likely to report concussions. Meanwhile, future pilots showed less self-report willingness and perceived that others were similarly unwilling to report concussions. Discussion: A majority of this economically and geographically diverse population displays characteristics of pluralistic ignorance: They largely share proconcussion reporting sentiments but incorrectly perceive that others do not. This belief is not held uniformly in all subpopulations, which may inform how these beliefs are developed and maintained. Conclusions: Pluralistic ignorance is an important consideration in concussion education efforts.

BackgroundIn recent years, the understanding of concussion has evolved in the research and medical communities to include more subtle and transient symptoms. The accepted definition of concussion in these communities has reflected this change. However, it is unclear whether this shift is also reflected in the understanding of the athletic community.What is known about the subjectSelf-reported concussion history is an inaccurate assessment of someone's lifetime exposure to concussive brain trauma. However, unfortunately, in many cases it is the only available tool.Hypothesis/purposeWe hypothesize that athletes' self-reported concussion histories will be significantly greater after reading them the current definition of concussion, relative to the reporting when no definition was provided. An increase from baseline to post-definition response will suggest that athletes are unaware of the currently accepted medical definition.Study designCross-sectional study of 472 current and former athletes.MethodsInvestigators conducted structured telephone interviews with current and former athletes between January 2010 and January 2013, asking participants to report how many concussions they had received in their lives. Interviewers then read participants a current definition of concussion, and asked them to re-estimate based on that definition.ResultsTHE TWO ESTIMATES WERE SIGNIFICANTLY DIFFERENT (WILCOXON SIGNED RANK TEST: z=15.636, P

Concussion underreporting contributes to the substantial public health burden of concussions from sport. Teammates may be able to play an important role in encouraging injury identification and help seeking. This study assessed whether there was an association between beliefs about the consequences of continued play with a concussion and intentions to engage as a proactive bystander in facilitating or encouraging teammate help seeking for a possible concussion. Participants were 328 (male and female) members of 19 U.S. collegiate contact or collision sports teams. Athletes who believed that there were negative health or performance consequences of continued play with a concussion were significantly more likely than their peers to intend to encourage teammate help seeking, but not more likely to alert a coach or medical personnel. Additionally, athletes who believed that their teammates were more supportive of concussion safety were more likely to intend to engage as proactive bystanders in encouraging teammate help seeking. Exploring how to encourage bystander promotion of concussion safety is an important direction for future programming and evaluation research and may provide an opportunity to improve the effectiveness of concussion education.

Concussion education for athletes has the potential to play a role in reducing the health burden of concussions from sport by modifying individual risk-related behaviors. In U.S. collegiate sport, decisions about content and delivery of concussion education are left up to the individual institution. This may result in a high degree of variability in what educational materials athletes receive and is particularly problematic as few concussion education programs have demonstrated efficacy. Health educators can play an important role in working collaboratively with sports medicine clinicians to design and evaluate evidence-based concussion education materials for athletes that meet their learning needs. As a first step in this process, the present study characterizes the content, source, and delivery modalities of concussion currently being provided to U.S. collegiate athletes. It also describes the reported concussion education preferences of a sample of U.S. collegiate athletes. Participants were 789 athletic trainers from 276 schools and 325 athletes from four schools. Results indicated that education is most frequently provided by athletic trainers but that many athletes would also like coaches and physicians to be involved in this process. Athletes also indicated a preference for content provision across a range of topics, including athletic and academic consequences of continued play with a concussion. Implications for the design and delivery of concussion education for athletes are discussed.

Secondary prevention of harm from sport-related concussion is contingent on immediate removal from play post-injury. To date, educational efforts to reduce the prevalent risk behavior of continued play while symptomatic have been largely ineffective. Social norms theory may hold promise as a foundation for more effective concussion education aimed at increasing concussion reporting. The primary objective of this study was to assess whether perceived team concussion reporting norms would be less supportive of an individual's safe concussion symptom reporting behavior than objective team norms. Participants were 328 male and female US collegiate athletes. Written surveys were completed in person during the spring of 2014. Among both male and female athletes, team concussion reporting norms were significantly misperceived, with athletes tending to think that they themselves have safer attitudes about concussion reporting than their teammates. Perceived norms were associated with symptom reporting intention, independent of the team's objective reporting norm. A social norms approach to concussion education, in which misperceived group norms are corrected and shifted in the direction of safety, is an important avenue for program development and evaluation research aimed at the secondary prevention of harm from concussion. Implications for the design of this type of educational programming are discussed.

Many states and sports leagues are instituting concussion policies aimed at reducing risk of morbidity and mortality; many include mandates about the provision of concussion education to youth athletes. However, there is limited evidence if educational materials provided under these typically vague mandates are in fact effective in changing concussion risk-related behavior or any cognition predictive of risk-related behavior. The purpose of this pilot randomized controlled study was to conduct a theory-driven evaluation of three publically available concussion education materials: two videos and one informational handout. Participants were 256 late adolescent males from 12 teams in a single league of ice hockey competition in the United States. Randomization of educational condition occurred at the team level. Written surveys assessing postimpact symptom reporting behavior, concussion knowledge, and concussion reporting cognitions were completed by participants immediately before receiving their educational intervention, 1 day after, and 1 month after. Results indicated no change in any measure over any time interval, with the exception of perceived underreporting norms. In one of the video conditions, perceived underreporting norms increased significantly 1 day after viewing the video. Possible content and viewing environment-related reasons for this increase are discussed. Across all conditions, perceived underreporting norms increased 1 month after intervention receipt, raising the possibility that late in the competitive season underreporting may be perceived as normative. The need for the development of theory-driven concussion education materials, drawing on best practices from health behavior scholars, is discussed.

The abrupt cessation of school and sport participation during the COVID-19 pandemic may have negative implications for adolescent mental health. To (1) compare mental, physical, and social health and behaviors during pandemic-related stay-at-home mandates with the same measures collected 1 to 2 years earlier and (2) evaluate the relationships between physical activity and sleep during the pandemic and changes in anxiety, fatigue, and peer relationships between assessment times. Cohort study. Pediatric sports medicine center. A total of 39 high school athletes (25 adolescent girls, 14 adolescent boys; age = 16.2 ± 0.9 years). Patient-Reported Outcome Measurement System anxiety, fatigue, and peer relationships short forms and the Pittsburgh Sleep Quality Index were completed twice (initial assessment in May 2018 or 2019, follow-up assessment in May or June 2020). Frequency and duration of physical activity and frequency of interaction with other individuals (family, peers, sport coaches, etc) were self-reported at follow-up assessment for the 2 weeks before school or sport closure and the 2 weeks before questionnaire completion. Higher levels of anxiety (5.5 ± 4.0 versus 3.6 ± 3.4 points; P =.003) and fatigue (5.4 ± 3.7 versus 2.3 ± 2.5 points; P <.001) and worse sleep quality (6.6 ± 2.9 versus 4.3 ± 2.3 points; P <.001) were observed during the pandemic compared with previous assessments. Reductions in physical activity were noted between assessments (exercise duration: 86.4 ± 41.0 versus 53.8 ± 30.0 minutes; P <.001). Sleep quality but not physical activity during the pandemic predicted changes in fatigue (P =.03, β = 0.44 [95% CI = 0.06, 0.83]) and peer relationships (P =.01, β = −0.65 [95% CI = −1.16, −0.15]) from initial to follow-up assessment. Mental and physical health declined during stay-at-home mandates compared with assessments 1 to 2 years earlier. Physical activity behaviors and sources of social interaction underwent changes after school and sport cessation. Sleep quality may have provided some protection against declining adolescent mental health during the pandemic, although this relationship requires further investigation. [ABSTRACT FROM AUTHOR]

Purpose: Assess whether athletes with a prior concussion diagnosis are more likely to continue play with a possible concussion. Additionally, explore whether reasons for concussion under-reporting are different among athletes with a prior concussion when compared to other athletes. Methods: Cross-sectional survey of 328 collegiate athletes. Results: Athletes with a prior concussion diagnosis had significantly greater relative risk of continuing play while symptomatic of a possible concussion during their most recent season compared to athletes without prior concussion diagnosis. Significant differences exist in the reasons that athletes provided for not reporting by history of concussion. Conclusions: Findings suggest that learning may have occurred as a result of the prior diagnosis; however, this learning did not appear to result in safer reporting behavior. Additional research is necessary to clarify why athletes who have been previously diagnosed with a concussion are more likely to continue playing while experiencing concussion symptoms. [ABSTRACT FROM AUTHOR]

This manuscript uses competitive college football as a lens into the complexities of decision-making amid the Covid-19 pandemic. Pulling together what is known about the decision-makers, the decision-making processes, the social and political context, the risks and benefits, and the underlying obligations of institutions to these athletes, we conduct an ethical analysis of the decisions surrounding the 2020 fall football season. Based on this ethical analysis, we provide key recommendations to improve similar decision processes moving forward. [ABSTRACT FROM AUTHOR]

Summary: Objective: This report estimates the percent of medically eligible adolescents who are referred for metabolic and bariatric surgery (MBS) evaluation or factors associated with referral. Methods: This cross‐sectional retrospective review evaluated patients aged 13 to 18 years seen between 2017 and 2019 for demographics, insurance status, body mass index (BMI), obesity‐related comorbidities, and compared these data to patients whom had been referred and received MBS. Results: Half of the patients (86 411/163137, 53%) between ages of 13 and 18 years identified had BMI documented, of which, 1974 (2.3%) were medically eligible for MBS, 238 (12%) were referred for MBS and 52 (22%) underwent MBS. Females had similar odds of being eligible for MBS [odds ratio (OR) = 1.01, 95% confidence interval (CI) 0.92‐1.11, P =.9], but greater odds of referral (OR = 1.58, 95% CI 1.13‐2.23, P =.009). Independently, miniorities and patients with public insurance had higher odds of being eligible for MBS, but similar odds of being referred as non‐Hispanic white patients. Black patients with public insurance had greater odds of being referred for MBS (OR = 12.22, 95% CI 2.08‐235.15, P =.022). Patients' multiple comorbidities had greater odds of being referred for MBS (OR = 2.16, 95% CI 1.29‐3.68, P =.004). Conclusions: Referral is barrier for patients medically eligible for MBS; however, this barrier is not uniformly faced by all patients. [ABSTRACT FROM AUTHOR]

Concussion underreporting leads to delays in diagnosis and treatment, prolonging recovery time. Athletes' self-reporting of concussion symptoms, therefore, reduces risk. To evaluate the effectiveness of 3 concussion-education programs in improving concussion-reporting intention. Randomized controlled clinical trial. Three high schools in California. A total of 118 male football players (age = 14.88 ± 1.19 years). Participants were randomly assigned to receive concussion education via CrashCourse (CC), Centers for Disease Control and Prevention (CDC) video education materials (CDC-Vi), or CDC written education materials (CDC-Wr). The primary outcome was concussion-reporting intention, which was assessed at baseline, immediately after education, and at 1-month follow-up. Secondary outcomes were concussion knowledge, concussion-reporting attitudes, perceived concussion-reporting norms, and perceived behavioral control. Across all education formats, a total sample of athletes improved in concussion-reporting intention at immediate and 1-month follow-ups (mean improvements = 6.8% and 11.4%, respectively; F4,224 = 11.1, P <.001). Similar findings were observed across all education formats in secondary analyses examining knowledge, attitudes, and perceived behavioral control. However, we noted differences in concussion-reporting intention by education format and time (F4,224 = 2.8, P =.03). Post hoc analysis showed that athletes who received CC had increased concussion-reporting intentions at immediate and 1-month follow-ups (baseline = 4.7, immediate follow-up = 6.1, 1-month follow-up = 6.0; F16,61.1 = 6.1, P =.007) compared with increases only at 1-month follow-up for CDC-Vi (baseline = 4.3, immediate follow-up = 5.2, 1-month follow-up = 5.8; F1.6,61.6 = 8.4, P =.001) and no improvement for CDC-Wr (P =.10). Secondary analyses indicated differences between CC and both CDC interventions in concussion knowledge and attitudes at immediate and 1-month follow-ups. We identified no differences in perceived behavioral control among interventions (F4,216 = 0.2, P =.93) or perceived concussion-reporting norms across (F4,224 = 0.3, P =.73) or among (F4,224 = 1.7, P =.15) interventions. All athletes exhibited an improved intent to report concussions, increased concussion knowledge, better concussion attitudes, and more perceived behavioral control at both immediate and 1-month follow-ups. However, athletes randomized to receive CC reported a greater intent to report concussion, more knowledge, and improved concussion-reporting attitudes when compared with those who received CDC-Vi and CDC-Wr. [ABSTRACT FROM AUTHOR]

ObjectivesMethodsResultsConclusionEvaluate professional rugby players’ self-reported perceived understanding of the head injury assessment (HIA) and return to play (RTP) processes and determine factors related to understanding and trust pertaining to these processes.An electronic survey measured concepts of interest. A thematic analysis of player understanding was performed, and player statements were coded.207 U.S. Major League Rugby (MLR) players participated (26.7 ± 3.4 years). HIA and RTP protocol understanding was not correlated with concussion history (p = 0.41). International rugby experience and trust regarding MLR support of the following protocols and opposing team medical staff practices varied in their relationship to HIA understanding. Trust that all MLR teams follow the same protocols was positively correlated with all HIA questions (ps < 0.03). No HIA questions were correlated with trust in their own team’s medical staff. All trust questions were significantly correlated with RTP process understanding. Qualitative analysis identified four HIA- and RTP-related themes: education needs, staffing needs, HIA criticisms, and importance of player safety.International playing experience and greater trust in the MLR and league stakeholders were associated with greater player understanding of the HIA and RTP protocols. These results provide insight into the importance of educating players on league-specific concussion protocols. [ABSTRACT FROM AUTHOR]

Context: A growing number of high-school-aged athletes participate on club sport teams. Some, but not all, state concussion laws apply to both interscholastic and private sport organizations. However, concussion education, management plans, and knowledge have not been examined in club coaches who coach high school-aged athletes. Objective: To determine if differences in concussion education, management plans, and knowledge exist between high school coaches and coaches of club sport teams. Design: Cross-sectional study. Setting: Online survey. Patients or Other Participants: A total of 769 coaches (497 high school coaches, 272 club coaches coaching high school-aged athletes; 266 women [34.6%], 503 men [65.4%]) completed an anonymous online questionnaire. Main Outcome Measure(s): The questionnaire consisted of demographic and team information, requirements for concussion- education and -management plans, and concussion knowledge. Results: High school coaches were more likely than club coaches to report that their organizing bodies or leagues required them to receive concussion-education information (97.4% versus 80.4%; P < .001) and that their organizing bodies or leagues had a concussion-management plan (94.0% versus 70.2%; P < .001). High school coaches were more likely than club coaches to correctly agree that most concussions resolve in 7 to 10 days (48.6% versus 40.1%; P= .02) and disagree that loss of consciousness is required to diagnose a concussion (87.1% versus 80.9%; P = .02). Conclusions: Club coaches were less likely to be aware of requirements for concussion-education and -management plans from their parent organizations and scored lower on specific concussion-knowledge questions than high school coaches despite the same education requirements across groups under their state concussion laws. These results raise concerns regarding the proper management of concussions in club sports and suggest a need for greater oversight and enforcement of state laws in the club sport setting. [ABSTRACT FROM AUTHOR]

Sports medicine clinicians face conflicts of interest in providing medical care to athletes. Using a survey of college football players, this study evaluates whether athletes are aware of these conflicts of interest, whether these conflicts affect athlete trust in their health care providers, or whether conflicts or athletes' trust in stakeholders are associated with athletes' injury reporting behaviors. [ABSTRACT FROM AUTHOR]

Context: The relative availability of clinicians as well as the types and training of health care providers have been associated with morbidity and mortality in non-athletic health care settings. Whether staffing variations are associated with injury incidence in collegiate athletes is unknown. Objective: To evaluate whether the institutional ratio of athletes to athletic trainers (patient load) or the ratio of staff to nonstaff (graduate assistant and certified intern) athletic trainers or both is associated with the incidence of injuries sustained by male ice hockey athletes at the school. Design: Descriptive epidemiology study. Setting: National Collegiate Athletic Association (NCAA) men's ice hockey teams. Patients or Other Participants: Collegiate men's ice hockey athletes. Main Outcome Measure(s): The NCAA Injury Surveillance Program collected data from collegiate men's ice hockey athletes. Staffing patterns were obtained through telephone interviews. Injury counts, injury rates per 1000 athlete-exposures, and injury rate ratios with 95% confidence intervals were calculated and compared between the following groups: (1) schools with high (versus low) patient load and (2) schools with high (versus low) ratio of staff to nonstaff (graduate assistant and certified intern) athletic trainers. Results: Both the patient load and relative number of staff athletic trainers were associated with variations in the incidences and types of diagnosed injuries in male ice hockey players. Specifically, fewer injuries were diagnosed by clinicians at institutions with high patient loads. The rates of injury overall and non-time-loss injuries were lower in the high patient-load group. Time-loss injury rates, severe injury rates, concussion rates, and overall rates of injury during competition were greater in the group with a higher proportion of staff athletic trainers, whereas non-time-loss injury rates were lower. Conclusions: In this study of collegiate men's ice hockey players, athlete health outcomes were directly related to the number and types of clinicians available. Future researchers should evaluate whether this finding extends beyond men's ice hockey. [ABSTRACT FROM AUTHOR]

Context: The ratio of clinicians to patients has been associated with health outcomes in many medical contexts but has not been explored in collegiate sports medicine. The relationship between administrative and financial oversight models and staffing is also unknown. Objective: To (1) evaluate staffing patterns in National Collegiate Athletic Association sports medicine programs and (2) investigate whether staffing was associated with the division of competition, Power 5 conference status, administrative reporting structure (medical or athletic department), or financial structure (medical or athletic department). Design: Cross-sectional study. Setting: Collegiate sports medicine programs. Patients or Other Participants: Representatives of 325 universities. Main Outcome Measure(s): A telephone survey was conducted during June and July 2015. Participants were asked questions regarding the presence and full-time equivalence of the health care providers on their sports medicine staff. The number of athletes per athletic trainer was determined. Results: Responding sports medicine programs had 0.5 to 20 full-time equivalent staff athletic trainers (median 4). Staff athletic trainers at participating schools cared for 21 to 525 athletes per clinician (median 100). Both administrative and financial oversight from a medical department versus the athletics department was associated with improved staffing across multiple metrics. Staffing levels were associated with the division of competition; athletic trainers at Division I schools cared for fewer athletes than athletic trainers at Division II or III schools, on average. The support of graduate assistant and certified intern athletic trainers varied across the sample as did the contributions of nonphysician, nonathletic trainer health care providers. Conclusions: In many health care settings, clinician : patient ratios are associated with patient health outcomes. We found systematic variations in clinician : patient ratios across National Collegiate Athletic Association divisions of competition and across medical versus athletics organizational models, raising the possibility that athletes' health outcomes vary across these contexts. Future researchers should evaluate the relationships between clinician : patient ratios and athletes' access to care, care provision, health care costs, health outcomes, and clinician job satisfaction. [ABSTRACT FROM AUTHOR]

Context: Structural features of health care environments are associated with patient health outcomes, but these relationships are not well understood in sports medicine. Objective: To evaluate the association between athlete injury outcomes and structural measures of health care at universities: (1) clinicians per athlete, (2) financial model of the sports medicine department, and (3) administrative reporting structure of the sports medicine department. Design: Descriptive epidemiology study. Setting: Collegiate sports medicine programs. Patients or Other Participants: Colleges that contribute data to the National Collegiate Athletic Association (NCAA) Injury Surveillance Program. Main Outcome Measure(s): We combined injury data from the NCAA Injury Surveillance Program, sports medicine staffing data from NCAA Research, athletic department characteristics from the United States Department of Education, and financial and administrative oversight model data from a previous survey. Rates of injury, reinjury, concussion, and time loss (days) in NCAA athletes. Results: Compared with schools that had an average number of clinicians per athlete, schools 1 standard deviation above average had a 9.5% lower injury incidence (103.6 versus 93.7 per 10000 athlete-exposures [AEs]; incidence rate ratio [IRR] = 0.905, P, .001), 2.7% lower incidence of reinjury (10.6 versus 10.3 per 10000 AEs; IRR = 0.973, P = .004), and 6.7% lower incidence of concussion (6.1 versus 5.7 per 10000 AEs; IRR = 0.933, P, .001). Compared with the average, schools that had 1 standard deviation more clinicians per athlete had 16% greater injury time loss (5.0 days versus 4.2 days; IRR = 1.16, P, .001). At schools with sports medicine departments financed by or reporting to the athletics department (or both), athletes had higher injury incidences (31% and 9%, respectively). Conclusions: The financial and reporting structures of collegiate sports medicine departments as well as the number of clinicians per athlete were associated with injury risk. Increasing the number of sports medicine clinicians on staff and structuring sports medicine departments such that they are financed by and report to a medical institution may reduce athlete injury incidence. [ABSTRACT FROM AUTHOR]

Athletes sometimes choose not to report suspected concussions, risking delays in treatment and health consequences. How and why do athletes make these reporting decisions? Using original survey data from a cohort of college football players, we evaluate two assumptions of the current literature on injury reporting: first, that the probability of reporting a concussion or injury is constant over time; second, that athletes make reasoned deliberative decisions about whether to report their concussion or other injury. We find that athletes are much less likely to report a concussion to a medical professional than they are to report another injury (47% vs. 80%), but no association between reporting and a measure of athletes' ability to switch from fast, reactive thinking to reasoned, deliberative thinking. The likelihood of reporting decreases as the number of injuries and concussions increases, and no athlete reported more than four concussions. Sports medicine clinicians sometimes use four concussions as a time to discuss possibly curtailing sports participation, which may influence athletes' subsequent reporting behavior. Sports medicine clinicians may want to consider athlete injury history as a risk factor for concussion and injury under-reporting. [ABSTRACT FROM AUTHOR]

Background: There were 18,844 volleyball players in the National Collegiate Athletic Association (NCAA) in the 2014-2015 academic year. Little research has examined sex-based differences among these athletes.Purpose: To examine injury epidemiology in NCAA men's and women's volleyball athletes.Study Design: Descriptive epidemiology study.Level Of Evidence: Level 3.Methods: Injury surveillance data from the 2013-2014 through 2014-2015 academic years were obtained from the NCAA Injury Surveillance Program for 6 men's and 33 women's collegiate volleyball teams. Injury rates per 1000 athlete-exposures (AEs) and injury rate ratios (IRRs) with 95% CIs were calculated. Time-loss (TL) injuries resulted in participation restriction for at least 24 hours, and non-time-loss (NTL) injuries resulted in participation restriction of less than 24 hours.Results: Overall, 83 and 510 injuries were reported in men and women, respectively, leading to injury rates of 4.69 and 7.07 per 1000 AEs. The injury rate was greater in women than men (IRR, 1.51; 95% CI, 1.19-1.90). TL injury rates were 1.75 and 2.62 per 1000 AEs for men and women, respectively. The ankle was the most commonly injured body part among TL injuries (men, 25.8%; women, 24.3%); the knee was the most commonly injured body part among NTL injuries (men, 25.5%; women, 16.3%). Among TL injuries, common diagnoses included sprains (men, 25.8%; women, 31.2%) and concussions (men, 19.4%; women, 14.8%). Most TL concussions were due to ball contact (men, 83.3%; women, 53.6%). Compared with men, women had a greater NTL overuse injury rate (IRR, 3.47; 95% CI, 1.61-7.46). Compared with women, men had a greater TL injury rate associated with ball contact (IRR, 2.24; 95% CI, 1.07-4.68).Conclusion: There are differences in injury patterns and rates between male and female intercollegiate volleyball players. Although a limited-contact sport, a notable number of concussions were sustained, mostly from ball contact.Clinical Relevance: Understanding injury patterns may aid clinicians in injury diagnosis, management, and prevention. [ABSTRACT FROM AUTHOR]

Importance: Players of American football may be at increased risk of long-term neurological conditions, particularly chronic traumatic encephalopathy (CTE).Objective: To determine the neuropathological and clinical features of deceased football players with CTE.Design, Setting, and Participants: Case series of 202 football players whose brains were donated for research. Neuropathological evaluations and retrospective telephone clinical assessments (including head trauma history) with informants were performed blinded. Online questionnaires ascertained athletic and military history.Exposures: Participation in American football at any level of play.Main Outcomes and Measures: Neuropathological diagnoses of neurodegenerative diseases, including CTE, based on defined diagnostic criteria; CTE neuropathological severity (stages I to IV or dichotomized into mild [stages I and II] and severe [stages III and IV]); informant-reported athletic history and, for players who died in 2014 or later, clinical presentation, including behavior, mood, and cognitive symptoms and dementia.Results: Among 202 deceased former football players (median age at death, 66 years [interquartile range, 47-76 years]), CTE was neuropathologically diagnosed in 177 players (87%; median age at death, 67 years [interquartile range, 52-77 years]; mean years of football participation, 15.1 [SD, 5.2]), including 0 of 2 pre-high school, 3 of 14 high school (21%), 48 of 53 college (91%), 9 of 14 semiprofessional (64%), 7 of 8 Canadian Football League (88%), and 110 of 111 National Football League (99%) players. Neuropathological severity of CTE was distributed across the highest level of play, with all 3 former high school players having mild pathology and the majority of former college (27 [56%]), semiprofessional (5 [56%]), and professional (101 [86%]) players having severe pathology. Among 27 participants with mild CTE pathology, 26 (96%) had behavioral or mood symptoms or both, 23 (85%) had cognitive symptoms, and 9 (33%) had signs of dementia. Among 84 participants with severe CTE pathology, 75 (89%) had behavioral or mood symptoms or both, 80 (95%) had cognitive symptoms, and 71 (85%) had signs of dementia.Conclusions and Relevance: In a convenience sample of deceased football players who donated their brains for research, a high proportion had neuropathological evidence of CTE, suggesting that CTE may be related to prior participation in football. [ABSTRACT FROM AUTHOR]