This study is Part 2 of data collection from 13-25 years old subject population for validation of previously derived algorithms. This data will be combined with that collected under NCT02957461 (Part 1 with subject age range 18-25 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 NCT02957461 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. Having sustained a traumatic closed head injury within 72 hours (3 days) from time of injury at time of BrainScope assessment;
2. GCS 13-15 at time of BrainScope assessment;
3. No hospital admission due to either head injury or collateral injuries for >24 hours.

For Matched Controls:

1. GCS 15 at time of BrainScope assessment;
2. No prior history of concussion or TBI in the last year.

Exclusion Criteria:

1. Previously enrolled in the BrainScope CAS Studies;
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. Subjects who do not speak English (non-English speaking parents are allowed to consent so long as translation of the consent form in their native language is available);
7. Acute intoxication;
8. Evidence of illicit drug usage;

For Injured subjects:

1. Loss of consciousness ≥ 20 minutes related to the concussion injury;
2. Active fever defined as greater than 100ºF or 37.78ºC at time of BrainScope assessment;
3. Evidence of abnormality visible on Computerized Tomography (CT) of the head related to the traumatic event (Note: neuroimaging is not required for enrollment).

For Matched Controls:

1. Any focal neurological signs including aphasia, apraxia, diplopia, facial droop, dysarthria/slurred speech;
2. History of Motor Vehicle Accident (MVA) requiring an Emergency Department visit within the past 1 year.

Approximately 160 Injured and Matched Control subjects will be recruited from high schools, college universities, concussion clinics and emergency rooms.