Recently, researchers and clinicians have examined many different forms of concussion testing aimed to assess if a brain injury has occurred and to what degree it affects the individual being tested. Due to the multifaceted and complex presentation of concussive injuries and the unknown effects of repeated head trauma, it is unlikely that a single test of physiological or behavioral function will reflect the full range of injury-related damages from a concussive event or from a series of cumulative head traumas, as well as the injury response within brain tissue. However, by combining a variety of objective assessments which may detect structural and functional alterations following head trauma into a single study, a clearer understanding of the multi-faceted presentation resulting from head trauma may be identified. The identification of biomarkers and the utilization of objective and clinically feasible tools will provide a method to assess three domains across multiple systems affected by head trauma: 1) the prognostic value of initial concussion assessments to identify injury severity and factors responsible for prolonged recovery, 2) the temporal window of recovery and potential vulnerability of brain tissue post-injury, and 3) the long-term alterations associated with repeated head trauma exposure.

Student athletes from contact and collision sports, as well as non-contact sports, will complete a comprehensive assessment of neurological and behavioral function before and after a season of participation. Additionally, those who sustain a concussion will undergo a post-injury testing timeline where they are assessed within 5 days of injury and again at the following time points: 3-4 weeks, 3 months, 6 months, and 1 year post-injury. Each individual who completes testing as a concussion subject will be matched with a healthy control subject by height, weight, age, sport, and position, and each control subject will complete the same protocol in similar time increments as subjects with concussion.

Through this study design, we hypothesize that we will be able to detect objective deficits resulting from concussion within one week of injury and determine the feasibility and added value of a comprehensive neurological and behavioral testing battery through a comparison of metrics between injured and healthy collegiate student athletes. Additionally, we hypothesize that for athletes who do not sustain a concussion, decrements between the pre-season and post-season time points will be greater in those who participate in collision/contact sports in comparison to those who participate in non-contact sports. Thus, outcomes from this study will enhance the understanding of the pathophysiology of concussion through a rigorous laboratory testing component, but with simultaneous direct translation to clinical implementation through the use of a highly-feasible clinical testing paradigm that possesses potential for ubiquitous and widespread use throughout sports medicine practices.

Inclusion Criteria:

1. Participation on a Harvard University varsity athletic team
2. Medically cleared to participate in sport, as determined by Harvard medical staff
3. Diagnosed with concussion by Harvard medical staff, and agreement to participate in the post-injury component of the study within five days of injury (post-concussion group)
4. No diagnosed concussion within the previous year of evaluation (control group)

Exclusion Criteria:

1. A history of epilepsy, prior seizure, or any previous abnormal EEG finding or abnormal brain imaging (CT or MRI) finding, as reported by the patient.
2. Any pre-existing neurological disorder, including but not limited to stroke, intracranial hemorrhage, any movement disorder, and cerebral palsy.
3. Any currently active psychiatric condition, including specifically major depression, bipolar disorder or schizophrenia. A history of a psychiatric condition but no ongoing psychiatric episode (e.g. not currently undergoing treatment for a major depressive episode) would not be an exclusion.
4. Any unstable medical condition
5. For the transcranial Doppler ultrasound component of the study only, subjects with infection, history of seizure, cardioactive drug participation, presence of deep vein thrombosis, cervical injury (structural or vascular), gross motor deficits, or skull fractures will be excluded.

Subjects will be comprised of active members of various varsity teams at Harvard University.