Concussion research: Moving beyond the natural history.

The topic of sports-related concussion has been, and will likely continue to be, one of the most challenging topics in sports medicine. The last 2 decades of research has fundamentally altered clinician's and the public's view of concussions from a relatively minor “ding” to be shaken off with rapid return to play to the current realization that concussions are brain injuries with potential lifelong consequences. The National Collegiate Athletic Association (NCAA) and the Department of Defense (DoD) Concussion Assessment, Research and Education (CARE) Consortium Study currently elucidating the natural history of concussion will provide clinicians critical recommendations on the diagnosis and management; however, many neuropsychosocial questions remain unanswered. Thus, this special topic on Emerging Concussion Research of the Journal of Sport and Health Science (JSHS) is dedicated to addressing key concussion related questions that extend beyond typical clinical concussion management to include broad public health-related concerns.

The preponderance of concussion research is focused on high school and college athletes as well as military members; however, in the opening paper, Kerr et al. investigated concussion attitude and knowledge in 1224 parents of middle school (Grades 5–9) students. Kerr et al. reported that women, white race, higher parental age, and greater competitiveness were associated with higher knowledge, while white race and older parental age were associated with more positive care-seeking attitudes. As concussions that occur early in life are associated with more subsequent concussions, early recognition and appropriate treatment are critical and the results of this study identify areas to improve parent's knowledge and attitudes before their children reach the high school level.

Parental knowledge and attitude are critical as parents can influence their children's decisions on sports participation and the risk of repetitive head impacts in sports remains an ongoing concern., In the 2nd article, Muñoz et al. investigated purposeful soccer heading and biomarkers (extracellular vesicles) in healthy adults and reported that heading altered extracellular vesicle plasma content, but not size or number of the vesicles. These findings further the use of blood borne biomarkers as an emerging assessment technique and provides an avenue to improve a mechanistic understanding on neurological effects of repetitive head impacts.

While biomarkers remain the next frontier in concussion research, existing clinical assessments are needed to improve the sensitivity and specificity of the current concussion assessment battery. Van Deventer et al. investigated the diagnostic utility of the tandem gait test in 126 pediatric concussion patients compared to 58 healthy individuals and reported slower single and dual task tandem gait performance. Similarly, Oldham et al. compared 30 post-concussion adolescents to 30 healthy individuals and found that eye tracking in concussion participants was an effective assessment tool and was closely associated with elevated symptom profiles. Taken together, these 2 studies provide potentially clinical approaches which may improve the psychometrics of the existing concussion battery.

An additional limitation of the concussion battery is the low sensitivity to determine recovery and neurophysiological deficits that exist beyond clinical recovery. However, the clinical implications of these persistent effects have not been well established and thus the next 2 papers in this special issue address this emerging area. First, Lempke et al. addressed the public health concern related to post-concussion driving. As impairments in motor control, reaction time, and neurocognition are known post-concussion deficits, the potential dangers associated with driving are considerable. In this study, 14 post-concussion participants who were self-reported symptom free were compared to 14 healthy controls on a driving simulator and a computerized neurocognitive test. The post-concussion participants had significantly delayed reaction time across a wide variety of driving tasks with medium to large effect sizes. Given the risk associated with an impaired driver, to both themselves and other community members, this study highlights a critical area to be addressed moving forward. Finally, Chmielewski et al. reviewed the existing literature related to concussion and subsequent musculoskeletal injury. Similar to Lempke et al., Chmielewski et al. reported on persistent deficits in motor control as a potential mechanism to the about 2 times elevated risk of post-concussion musculoskeletal injury. Taken together, these 2 papers reinforce the need for clinicians to investigate and rehabilitate motor control more comprehensively following a concussion.

The majority of concussion related research has focused on football given the high absolute number of concussions which occur; however, this limits the understanding of sex as a biological variable in concussion research. The final paper in the special issue by Van Pelt et al. addressed this topic by investigating concussions in both men's and women's collegiate ice hockey teams engaged in the CARE study. While there were no sex differences in concussion mechanisms, females were less likely to have delayed onset of symptoms and took longer to be asymptomatic and return to play, further acknowledging that sex is an important consideration in concussion management. This finding extends prior work on sex differences, but is unable to differentiate physiological, psychological, or sociological influences on concussion related symptoms.

We are excited to bring present these articles that address critically important and emerging topics in concussion management. The topics of blood biomarkers, improved postural control assessments, persistent neurophysiological deficits, and sex differences in concussion recovery are at the frontier of concussion related challenges. We appreciate the authors' timely submission of these manuscripts during the coronavirus disease-2019 (COVID-19) pandemic as well as the reviewers who provided valuable insights to improve the manuscripts. Finally, we thank the editorial board and staff at the JSHS for facilitating the special topic and their support throughout the process.

Competing interests

The author declares that he has no competing interests.