This study is Part 1 of data collection from 18-25 years old subject population for validation of previously derived algorithms. This data will be combined with that collected under NCT03671083 (Part 2 with subject age range 13-25 years) for the final analyses of validation of the algorithms.

EEG, neurocognitive performance and clinical data will be collected at time of injury (within 3 days) at clinically determined Return to Play (RTP) and 45 days after RTP, for the purpose of independently validating the performance of the algorithms developed in prior studies (NCT02477943, NCT02661633 and NCTXXXXXX). Data collected under this study will be combined with that collected under NCT03671083 for the final analyses of prospective algorithm performance in an independent population ages 13-25 years. Subjects will come from the sports and other populations of concussed individuals. They will be matched with controls i.e. not head injured subjects who will also undergo the same set of tests and the same time intervals as the injured subjects. An additional pool of uninjured (not head injured) subjects will be collected who will be assessed at a single time point.

Inclusion Criteria (For Injured Subjects):

1. Time of injury within 72 hours of BrainScope Battery
2. No evidence of abnormality visible on Computerized Tomography (CT) of the head related to the traumatic event (Note: neuroimaging is not required for enrollment)
3. No hospital admission due to either head injury or collateral injuries for >24 hours
4. GCS between 13-15

Exclusion Criteria:

1. Previously enrolled as an Injured or Matched Control subject in the BrainScope Algorithm Development Study
2. Current CNS active prescription medications taken daily, with the exception of medications being taken for the treatment of Attention Deficit Disorder (ADD) or Attention Deficit Hyperactivity Disorder (ADHD)
3. Forehead, scalp or skull abnormalities that prevents headset application or EEG data collection
4. History of brain surgery or neurological disease
5. Pregnant women
6. Do not speak or read English
7. Loss of consciousness ≥ 20 minutes related to the concussion injury - for injured subjects only
8. Prior history of concussion in the last year - for Matched Control subjects only

Approximately 220 male and female student-athletes from participating universities or colleges will be invited to participate.