Cerebral Autoregulation, Brain Perfusion, and Neurocognitive Outcomes After Traumatic Brain Injury

Inclusion Criteria: * Documented/Verified TBI (ACRM Criteria) (eg, motor vehicle (MV) occupant, MV pedestrian/cyclist, fall, other non-intentional, violence/assault) * A documented moderate to severe TBI defined as: Glasgow Coma Scale (GCS) \< 13, or loss of consciousness (LOC) \> 30 minutes, or posttraumatic amnesia (PTA) \> 24 hours or intracranial neuroimaging abnormalities * Between the age 18 - 80 year-old * ≤ 1 week postinjury * Acute brain CT for clinical care * Admitted to the hospital for TBI * Visual acuity/hearing adequate for testing * Fluent in English or Spanish * Patient or LAR ability to provide informed consent Exclusion Criteria: * Age greater or less than the range 18-80 years * Significant polytrauma that would interfere with follow-up and outcome assessment * Major debilitating baseline mental health disorders (e.g., schizophrenia, bipolar disorder, severe depression with active suicidal thoughts at the time of evaluation) that would interfere with follow-up and the validity of outcome assessment. * Major debilitating neurological disease (e.g., stroke, CVA, dementia, tumor) impairing baseline awareness, cognition, or validity of follow-up and outcome assessment. * Significant history of pre-existing conditions that would interfere with follow-up and outcome assessment (e.g., active substance abuse, alcoholism, HIV/AIDs, end-stage cancers, learning disabilities, developmental disorders) * Patients on psychiatric hold * Prisoners or patients in custody * Pregnancy in female subjects * Low likelihood of follow-up (e.g., participants or family indicating low interest, residence in another state or country, homeless or lack of reliable contacts) * Current participant in an interventional trial (e.g., drug, device, behavioral) * Penetrating TBI * Spinal cord injury with ASIA score of C or worse * Contraindications to MRI