MORE THAN 1.6 MILLION AMERICANS have been deployed for service in Afghanistan and Iraq. These conflicts have resulted in more than 4800 deaths and 32,000 injuries to our service members.1 Among these injuries, significant attention has been focused on traumatic brain injury (TBI), posttraumatic stress disorder (PTSD), sensory loss (hearing and vision), and other combat-related conditions. Posttraumatic stress disorder has been a significant concern because of the extended and sometimes multiple tours that our service members take, coupled with repeated, in some respects constant, exposure to emotionally traumatic situations. According to internal Defense and Veterans Brain Injury Center data, between January 2003 and the end of September 2008, 8470 individuals with TBI were seen across its network, with more than 1700 seen at Walter Reed Army Medical Center. Of those who received injuries severe enough to warrant transfer to the level of care provided at Walter Reed, about 33% also suffered TBI. Overall, this incidence, though reflective of the majority of those in the moderate to severe range of TBI, does not represent all those who suffered TBI while deployed. This number is unknown because many may not have been properly evaluated or treated.

The Army and Marine Corps have instituted screening for mild TBI in most service members returning home who may have sustained an injury during their deployment. The results of these screening efforts suggest that as many as 10% to 20% may have suffered a concussion (mild TBI) during the time they were deployed.2 This percentage is consistent with the 19.5% prevalence estimated in the Rand survey, which represents about 320,000 service members. While these rates are alarming to the general public, the majority of service members who suffer concussions will recover uneventfully. Nonetheless, they may have short-term consequences of their injury that may affect functioning or military readiness. It can be expected that some percentage of those with mild TBI will have symptoms that persist beyond their deployment, and some will experience persistent consequences as disabling as those experienced at the severe end of the TBI spectrum. For those who suffer TBI in the context of other significant extracranial injuries, their recovery can be expected to be slow,3 and their struggles with pain and stress may further affect functioning.

Brain injury is as old as warfare. Earlier in the last century, the work of Newcombe,4 Luria,5,6 and Rosvold et al7 advanced our understanding of brain functioning by studying those who suffered brain injuries in combat during World War I and World War II. Later in the century, Grafman8 and Carey et al9 examined those who suffered penetrating brain injuries in Vietnam, and their work increased our understanding of focal brain pathology and its effects on functioning in multiple domains. In short, with the tragedy comes an opportunity. It is our obligation to those injured to use the knowledge and experience gained in these conflicts to improve the care of their fellow service members and, as much as possible, generalize this knowledge to the population as a whole. Each conflict has unique elements that may advance our understanding. In this war, the explosive device has been the enemy's weapon of choice. There are multiple active investigations around blast and how it might be different from more traditional, mechanically induced closed TBI. Unfortunately, these investigations have relevance to our everyday lives as we face potential terrorist threats.10

This issue of the Journal of Head Trauma Rehabilitation (JHTR) is about TBI in the military. This is a very broad topic that can potentially cover policy issues, identification, treatment, and outcome. Concerns about TBI in a military context encompass the range of severity, from the mildest concussion to death, as well as intervention from primary prevention to secondary prevention at the point of injury on the battlefield and intervention throughout the lifespan. Obviously, a single issue of JHTR cannot begin to address all the potential topics of interest. Nonetheless, the range of topics presented in this issue is broad and touches on many of the pressing issues faced by the healthcare systems in both the Department of Defense (DoD) and the Department of Veterans Affairs (VA).

The articles in this issue of JHTR are not without controversy. Two of the articles directly address issues of screening in the military population. Another, among other topics, discusses TBI screening in the VA system. There is no doubt that quickly identifying those who have suffered TBI is the ideal, even if it is a mild TBI. Such identification may prevent premature return to duty before full recovery and avoid putting the military mission at risk or exposing comrades to risk of harm. Furthermore, early identification would protect service members during a vulnerable time when further action could expose them to more serious consequences or morbidity. However, it is less clear whether there is value screening for such mild TBI significantly after the fact. Retrospective screening increases the possibility for both false positives and false negatives and raises the possibility of misattribution of symptoms with possible iatrogenic effects. If the screening occurs even more remotely, after the postdeployment health screening process, and at the point a service member seeks treatment in the VA system, these problems may be magnified. Or, as current VA and DOD policy dictates, identification of such individuals may allow for targeted treatments and follow-up that might not otherwise have occurred.

Belanger and colleagues11 outline the current VA TBI screening process and discuss the difficulties inherent in such a large-scale effort. Terrio and colleagues12 report on the results of a postdeployment screen for a brigade combat team. Almost 23% showed clinician-confirmed TBI (almost all mild) during their deployment. As one would expect, those with TBI endorsed high rates of symptoms for the acute period following injury but improved over time. This finding should be reassuring. Even in what one would expect to be a poor environment for recovery, most individuals appear to be getting better.

Ivins et al13 discuss the baseline cognitive testing that the DOD has implemented. The goal of this testing, when done before deployment, is to establish a cognitive baseline that can be used for comparison purposes after TBI in the theater of operations, or for comparison with postdeployment results to investigate deployment-related cognitive effects. The potential advantage of such information must be balanced by the impact of serial cognitive testing of individuals or the difficulties in detecting what is a clinically meaningful change in test performance. In the war zone, the effects of fatigue, stress, or other factors that may affect cognition must also be considered. The article by Ivins et al, consistent with previous work, calls into question the use of an automated test measure to detect cognitive changes after mild TBI some number of months postinjury.

Other articles in this issue address rehabilitation for TBI patients in the military population, as well as other issues that may affect outcome. Rosen and colleagues14 present an overview of the use of driving simulators in cognitive rehabilitation of combat returnees with TBI. Our clinical experience in the DOD is that an uninjured service member also needs help transitioning from the "battlemind" back to everyday life and experience. For example, driving styles in a combat vehicle in a combat zone do not translate well to our roads here in the United States. While these uses are not discussed in depth in this article, Rosen and colleagues discuss the importance of assessing individuals in more "real-life" ways. Driving simulations are one possible way of increasing the ecologic validity of our assessments.

Besides the risk of TBI in the combat zone, individuals are exposed to emotionally traumatic events that, even if they do not result in a diagnosable mental disorder, nonetheless may affect functioning. In those service members who do suffer a TBI or develop a PTSD, there is concern that there may be interactive effects between stress symptoms and mild TBI that can affect outcome from either. Nelson and colleagues15 investigate neuropsychologic profiles of those with combat-related mild TBI and compare with those who also meet criteria for PTSD. Some potential implications for treatment based on their findings are discussed.

Weichel and colleagues16 look at the relationship between combat ocular trauma and TBI. In this sample from Walter Reed, 21% of the TBI patients had ocular trauma, though the presence of TBI did not result in poorer visual outcomes. Their article touches on the potential impact on treatment of cognitive dysfunction and other potential TBI-related symptoms. The unknown question, and perhaps of more interest to our readers, is how sensory dysfunction such as visual or hearing loss affects TBI outcomes in the combat-injured soldiers. Fortunately, research is in progress to examine these issues, as well as pain, lengthy rehabilitation, and other factors affecting the military polytrauma patient.

Moving beyond contextual issues of the injuries, as well as comorbid conditions, the final article in this issue looks at the impact of an individual's genetic status as a factor in recovery for those with mild to moderate TBI. Han and colleagues17 examine the influence of the APOE4 gene in association with other neurocognitive and clinical symptoms on changes in job status soon after injury.

In short, the issue provides readers a sense of some of the relevant issues and pressing concerns related to TBI in a military population, as well as some of the larger political influences that affect care delivery and research. Congress has allocated significant resources toward clinical care and research for TBI and PTSD in the combat-injured population. This generosity has brought with it not only significant opportunity but also significant responsibility. Resources need to be used in a scientifically sound way while still respecting the political reality of our time. If, for example, Congress mandates predeployment cognitive testing in the military, it is our job as brain injury researchers and clinicians, as much as possible, to design its implementation to be the most valid and meaningful from a clinical and scientific standpoint. Education about the issues and concerns in this population is an important first step forward. It is our hope that this issue moves us in that direction.

On a personal note, I have been deeply involved in clinical care and policy development related to TBI in the DOD since the beginning of our country's involvement in Afghanistan. This work has been difficult in many ways and has affected me significantly. Although it is probably obvious, I think it is important to state again-there are significant sacrifices made every day by those in uniform. These sacrifices are obvious in the injured, but they occur on many other levels too through multiple and extended deployments and the effects on the individual and their families. No one returns from war unaffected. It has been my honor to serve with these brave individuals-the service members I see every day-and the uniformed healthcare providers who show such dedication and compassion in treating the injured soldiers.

Louis M. French, PsyD

Walter Reed Army Medical Center, Defense and Veterans Brain Injury Center, Uniformed Services University of the Health Sciences, Washington, DC

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