There is little doubt as to the existence of persistent post concussive symptoms (PPCSx) more than three months post concussion. However, much controversy exists as to the cause of such persistent symptoms, with some claiming that they are not directly due to concussion per se, but instead from psychological disorders such as Posttraumatic Stress Disorder (PTSD) and depression. Data from 12,000 recently deployed service members reveal that the strongest predictor of PPCSx is indeed PTSD and depression. However, a subset of service members complaining of PPCSx cannot be explained by psychological variables. Additional research revealed that post-deployment service members with PTSD who also suffered from concussion have greater autonomic dysregulation than those with PTSD alone. Together, this research suggests that it is preliminary to discount the possibility that a subset of those complaining of PPCSx have persistent problems due exclusively to PTSD and depression.