HBOT Effects on First Responders' Cognition and Well-Being

The goal of this study is to examine changes in cognitive functioning and post-concussive symptoms following hyperbaric oxygen therapy (HBOT) in current and former first responders with a history of traumatic brain injury. The main questions it aims to answer are: 1. Do cognitive functioning and post-concussive symptoms change after 40 HBOT sessions? 2. Do symptoms of PTSD, depression, and anxiety, or quality of life, change after treatment? Approximately 54 participants will: * Complete medical and behavioral health screening. * Complete cognitive tests and questionnaires before and after treatment. * Receive 40 HBOT sessions at 2.0 atmospheres absolute (ATA), twice daily with at least four hours between sessions. All participants will receive HBOT. There is no comparison group, so the study cannot determine whether HBOT caused any observed changes.