Normative Datasets for Assessments Planned for Mild Traumatic Brain Injury (NORMAL)

The primary purpose of this study will develop a database from normal healthy participants for the same outcomes used in a program of studies of hyperbaric oxygen (HBO2) vs. sham control in participants with persistent post-concussive symptoms. This study will characterize the distribution of responses and change in responses over time for each of the outcomes and will examine associations between measures within a given normal participant and across participant characteristics such as age and gender. It will evaluate the test-retest reliability of a series of assessments anticipated for use in the primary, secondary, and exploratory outcomes of this program of studies. A secondary purpose of this study is to compare normative values to results from randomized exploratory studies of HBO2 vs. sham control in participants with persistent post-concussive symptoms. Also, investigators will examine relationships between outcome measures from normal participants (with respect to clinical equivalence, participant burden, and risk) and compare to associations observed in other studies. In this study, normal, healthy, non-brain injured civilians and military participants (active or inactive) will undergo a battery of outcome assessments at defined test intervals to replicate the assessment battery used in a program of studies investigating the safety of HBO2 in patients with post-concussive symptoms following mild traumatic brain injury (TBI). The planned comprehensive assessments will obtain robust neuropsychological, physiological, and neuroimaging data. Other evaluations will include laboratory testing and evaluations of the auditory, vestibular, and visual systems. Neuroimaging (magnetic resonance imaging and computed tomography angiography) will be assessed in participants at baseline and 6 months. Neurological function and electroencephalography (EEG) will be assessed at baseline only. All other in-person outcome measures will be assessed in participants at baseline, at 13 weeks, and 6 months.