A Systematic Review: Complications of Mild Traumatic Brain Injury in Veterans and Military Personnel
Traumatic brain injury (TBI) is a common condition, especially among military members, with 12% to 23% of service members returning from Operations Enduring Freedom, Iraqi Freedom, and New Dawn (OEF/OIF/OND) having experienced a TBI while deployed. Although various criteria are used to define TBI severity, the majority of documented TBI events among OEF/OIF/OND service members may be classified as mild in severity, or mTBI, according to the definition used by VA and the Department of Defense.
While some researchers suggest most individuals recover within three months of a mTBI, others estimate that 10% to 20% of individuals continue to experience post-concussive symptoms (e.g., headaches, dizziness, and balance problems) beyond this time frame. This estimate may be higher among OEF/OIF/OND service members given the frequency of multiple TBI events, concomitant mental health conditions (i.e., depression and PTSD), and other factors unique to combat deployments. As such, deployment-related mTBI is a significant issue for the VA as Veterans who report ongoing mTBI symptoms may require attention from a range of healthcare professionals.
Investigators with the VA Evidence-based Synthesis Program, located within the Portland VAMC, conducted a review of the literature using Medline, PsychINFO, and Cochrane Register of Controlled Trials from database inception through October 3, 2012, in order to assess prognoses for Veterans or military personnel after suffering a mTBI. Investigators identified 31 studies that met their inclusion criteria in order to answer the following key questions.
For Veteran/military populations, what is the prevalence of physical health problems (e.g., pain, seizure disorders, headaches, and vertigo), cognitive deficits, functional limitations (e.g., employment status, changes in marital status/family dynamics), and mental health symptoms (e.g., PTSD and depression) that develop or persist following mTBI?
What factors affect outcomes for Veteran/military patients with mTBI?
For Veteran/military populations, are there pre-injury (pre-morbid) risk/protective factors (e.g., pre-injury mental health factors, genetic factors, or prior concussions) that affect outcomes for mTBI?
For Veteran/military populations, are there post-injury risk/protective factors (e.g., PTSD) that affect outcomes for mTBI?
What is the resource utilization over time for Veteran/military patients with mTBI?
Investigators found 17 studies that reported physical health outcomes for those with mTBI, and low-strength evidence suggests that self-reported physical symptoms are associated with mTBI. Symptoms commonly reported by those with mTBI include: headaches, pain, vestibular symptoms, hearing and vision problems, nausea or loss of appetite, and neurologic symptoms, though symptom severity ranged widely across individuals. It is unclear whether mTBI directly contributes to the prevalence or severity of physical health symptoms, as only two studies included a comparison group of participants without mTBI.
Investigators found 17 studies that reported cognitive outcomes for those with mTBI.
- Objective Cognitive Tests: Overall, few studies found an association between mTBI and objective cognitive deficits. Though there were studies that found mTBI patients had deficits in visuospatial abilities, attention/concentration, and composite cognitive scores as compared to patients without mTBI, findings were inconsistent across studies. Impaired cognitive test performance was associated with comorbid mental health diagnosis, time since injury of less than 10 days, and self-reported cognitive complaints.
- Self-Reported Cognitive Problems: Self-reported cognitive complaints were common, both in Veterans with and without mTBI. Correlates of more severe self-reported cognitive problems include being service connected, and having an Axis I mental health disorder.
Functional Limitations and Social Outcomes
Investigators found 12 studies that reported functional/social outcomes for Veterans or members of the military with mTBI. One study reported that approximately 20% of Veterans with mTBI experience unemployment. One study comparing participants with and without mTBI found higher unemployment among those with mTBI, though another study found similar rates for Veterans with and without mTBI. Another study found that 26% of those with mTBI had difficulties with interpersonal relationships, though this is comparable to rates of similar Veterans without mTBI. And two studies found an overall prevalence of sleep disturbance for those with mTBI of 13-23%.
Investigators found 20 studies that reported mental health outcomes for Veterans or members of the military with mTBI. These studies suggest that there are high rates of mental health disorders and symptoms reported by Veterans and members of the military who have a history of mTBI. The majority of included studies suggest that there are few, if any, significant differences in mental health outcomes for those with mTBI compared to Veteran/military participants who have similar combat experiences without mTBI.
Investigators found seven low-quality studies that described service utilization by those with mTBI, but no studies that reported costs associated with mTBI. The available literature suggests that there are few differences in service utilization for those with mTBI compared to similar Veterans without mTBI.
The 31 studies included in this report were low-quality, cross-sectional studies that did not provide consistent evidence for potential moderators of mTBI outcomes. Most studies did not report prevalence estimates of impairment or comparisons to similar Veteran/military control group participants without mTBI. Overall, the strength of evidence in this review is low due to methodologic study limitations, small sample size, and inadequate reporting of and accounting for time since injury.
Overall, given the low strength of evidence, it is difficult to draw firm conclusions about the effects of mTBI in Veteran and military populations. The literature reviewed here is relatively consistent with findings from the more methodologically rigorous, prospective, longitudinal studies conducted in civilian populations. Both bodies of literature suggest that though some negative outcomes occur for a significant portion of individuals who have mTBI, most objective results (e.g., objective cognitive test results) are not significantly different from control participants, and deficits that are present shortly following injury most often resolve within days to months. The literature on Veterans and members of the military suggests that many have physical and mental health symptoms. It is not clear that those with mTBI experience more or higher severity symptoms than those without mTBI, which suggests that outcomes may be influenced by other deployment-related conditions such as PTSD.
Many symptoms that patients ascribe to mTBI may be related to comorbid mental or physical health concerns, or to other factors such as readjustment to civilian life following deployment, injury beliefs, and perceptions. Difficulties related to post-deployment adjustment underscore the need to engage recently returned Veterans and members of the military in efforts to identify physical and mental health problems and to provide appropriate re-integration services. Patients should be encouraged to engage in treatment for these comorbid concerns with the best available evidence-based treatments for PTSD, as well as substance use disorders, headaches, sleep disorders, and other post-deployment concerns. The current evidence base suggests that cognitive deficits are not common, particularly more than three months after injury. Therefore, should individuals with mTBI continue to experience ongoing cognitive deficits following first-line treatment for co-occurring symptoms and disorders (e.g., PTSD), further testing such as neuropsychological or neurological evaluations or imaging might be warranted.
David X. Cifu, M.D., Chair of VA's Traumatic Brain Injury Advisory Committee and National Director of VA's Physical Medicine & Rehabilitation Program, stated, "This report highlights VA's efforts to remain at the cutting edge of TBI research and care using state-of-the-art research and data synthesis techniques. It also emphasizes the need for large-scale, longitudinal cohort studies of service members and Veterans — with and without mTBI exposure — to better understand the short- and long-term effects of combat-associated mTBI and related comorbidities on the physical, psychological, and functional status of these individuals."
Future research on Veterans and members of the military should not only report time since injury for their research populations, but specifically account for time since injury in analyses. There is a pressing need for large cohort studies of Veterans with and without mTBI that prospectively collect data on risk and protective factors, and all outcomes of interest. Such studies would be relatively costly but would result in higher-quality evidence on which more definitive conclusions could be based.
A Cyberseminar session on this ESP Report was held on Tuesday, March 26, 2013 at 12:00pm (ET). View archive here.
This report is a product of VA/HSR&D's Quality Enhancement Research Initiative's (QUERI) Evidence-Based Synthesis Program (ESP), which was established to provide timely and accurate synthesis of targeted healthcare topics of particular importance to VA managers and policymakers — and to disseminate these reports throughout VA.
O'Neil ME, Carlson KF, Storzbach D, Brenner LA, Freeman M, Quiñones A, Motu'apuaka M, Ensley M, Kansagara D. Complications of Mild Traumatic Brain Injury in Veterans and Military Personnel: A Systematic Review. VA-ESP Project #05-225; 2012.
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