PubMed Health. A service of the National Library of Medicine, National Institutes of Health.

O'Neil ME, Carlson K, Storzbach D, et al. Complications of Mild Traumatic Brain Injury in Veterans and Military Personnel: A Systematic Review [Internet]. Washington (DC): Department of Veterans Affairs (US); 2013 Jan.



Traumatic brain injury (TBI) is a common condition, especially among military members. Twelve to 23 percent of service members returning from Operations Enduring Freedom, Iraqi Freedom, and New Dawn (OEF/OIF/OND) 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 the Veterans Health Administration and Department of Defense (VA/DoD).

While some researchers suggest most individuals recover within three months of an mTBI, others estimate that 10 to 20 percent of individuals continue to experience post-concussive symptoms (e.g., headaches, dizziness, balance problems) beyond this time fame. This estimate may be higher among OEF/OIF service members given the frequency of multiple TBI events, concomitant mental health conditions such as depression and posttraumatic stress disorder (PTSD), and other factors unique to combat deployments. As such, deployment-related mTBI is a significant issue for the VA, as patients who report ongoing mTBI symptoms may require the attention from a range of health care professionals. This evidence synthesis review will be used by the VHA TBI Advisory Committee to develop strategies to identify those at-risk for long-term mTBI effects, inform clinical practice, determine resource allocation, and identify future research priorities.

The key questions were:

Key Question #1. For Veteran/military populations, what is the prevalence of health problems (such as pain, seizure disorders, headaches, migraines, and vertigo), cognitive deficits, functional limitations (such as employment status, changes in marital status/family dynamics), and mental health symptoms (such as PTSD and depression) that develop or persist following mTBI?

Key Question #2. What factors affect outcomes for Veteran/military patients with mTBI? Key Question 2A: For Veteran/military populations, are there pre-injury (premorbid) risk/protective factors (e.g., pre-injury mental health factors, genetic factors, or prior concussions) that affect outcomes for mTBI? Key Question 2B: For Veteran/military populations, are there post-injury risk/protective factors (e.g., PTSD) that affect outcomes for mTBI?

Key Question #3. What is the resource utilization over time for Veteran/military patients with mTBI?


We searched Medline, PsychINFO and Cochrane Register of Controlled Trials (OVID), from database inception to October 3, 2012. We adapted the search strategy developed by the World Health Organization (WHO) Collaborating Centre for Neurotrauma Prevention, Management and Rehabilitation Task Force for a recent systematic review of prognosis after mTBI, and we included terms to identify articles specific to Veterans and military personnel. We obtained additional articles from systematic reviews, reference lists of pertinent studies, reviews, editorials, and by consulting clinical and research experts in the area of mTBI.

We included studies reporting outcomes in Veterans or military personnel who had suffered an mTBI using a case definition consistent with definitions in the VA/DoD Clinical Practice Guideline for Management of Concussion/Mild Traumatic Brain Injury. Reviewers trained in the critical analysis of literature assessed the titles and abstracts for relevance, and retrieved full-text articles for further review. We compiled a narrative synthesis of findings. We assessed individual study quality using criteria based on the Newcastle-Ottawa quality assessment tools for observational studies. We assessed the overall strength of evidence for the body of included literature according to criteria developed by the GRADE Working Group.

A draft version of this report was reviewed by 11 technical experts, as well as clinical leadership. Reviewer comments were addressed and our responses were incorporated in the final report (Appendix G).


From 2,668 titles and abstracts, we identified 354 articles for full-text review. Of these, 31 primary studies met inclusion criteria. In general, we found that though self-reported cognitive, physical, and mental health symptoms were common in the Veteran/military population, there was little evidence that symptoms were more common in those with mTBI than those without mTBI. However, the evidence base is weakened by inconsistent findings, methodologic shortcomings of many studies, and variation in outcomes considered and outcome measurement approaches. The following sections detail findings by symptom category.

Summary of Cognitive Functioning Results

We found 17 studies reporting cognitive outcomes for those with mTBI. Overall, few studies found an association between mTBI and cognitive deficits. The strength of evidence is low overall because of poor and incomplete reporting of data and sampling procedures, lack of time-since-injury information, and because most studies were unblinded and single-center.

There were studies that found mTBI patients had deficits in visuospatial abilities, attention/concentration, and total/cross-domain composite scores as compared to patients without mTBI. However, even within each of these subdomains, findings were inconsistent across studies. In nearly all studies, scores for each of the subscales fell within normal limits, suggesting no clinically significant impairment in the group as a whole. Because studies did not report the proportion of patients scoring below normal range for each of the subscales, it is unclear whether there may have been subgroups of mTBI patients with cognitive deficits.

It is difficult to draw overall conclusions about which factors, in addition to mTBI, are independently associated with cognitive test performance since studies evaluated a variety of different factors and there were inconsistent findings among studies. Impaired cognitive test performance was associated with comorbid mental health diagnosis, time since injury of less than 10 days, self-reported cognitive complaints, and experiencing loss or alteration of consciousness at the time of injury.

Self-reported cognitive complaints were common, both in Veterans with and without mTBI. Correlates of more severe self-reported cognitive problems include having an additional injury, loss of consciousness (LOC) or post-traumatic amnesia (PTA) at the time of injury versus only experiencing alteration of consciousness (AOC), being service connected, and having an Axis I mental health disorder.

Summary of Physical Health Results

We found 17 studies reporting physical health outcomes for those with mTBI. Low strength evidence suggests that self-reported physical symptoms are associated with mTBI. This body of evidence is comprised entirely of low quality studies generally limited by poor and incomplete reporting of data and sampling procedures, by lack of time-since-injury information, and because most studies were unblinded and single-center.

Studies included in this report suggest that symptoms commonly reported by those with mTBI include headaches, pain, vestibular symptoms, hearing and vision problems, nausea or loss of appetite, and neurologic symptoms. One study reported that the prevalence of neurology referrals for headaches was 33.3% for Veterans with mTBI, though no other physical health studies reported prevalence estimates for these outcomes. It is also 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. Symptom severity ranged widely across individuals and many of the physical health outcomes were based solely on responses to an individual item from the Neurobehavioral Symptom Inventory (NSI), a general post-concussive symptom inventory. Additionally, inconsistent information on risk and protective factors provided insufficient evidence to make strong conclusions about potentially moderators of physical health outcomes.

Summary of Mental Health Results

Twenty studies reported mental health outcomes for Veterans or members of the military with mTBI. Mental health outcomes varied greatly in terms of methods of assessment, ranging from lengthy clinical interviews based on diagnostic criteria, to single-item, self-report screeners. Overall, this body of literature provides low strength evidence, as it is based on low quality studies with many methodological limitations.

Studies included in this review 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. Prevalence of Axis I mental health disorders ranged from 50-78% in two studies; single studies reported that the rate of PTSD was 45%, alcohol abuse/dependence was 28%, drug abuse/dependence was 9%, suicidal ideation was 25%, suicidal intent was 7%, and past suicide attempts was 4% for Veterans with mTBI. Notably, however, 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 without mTBI. Finally, though many individual studies investigated potential moderating factors for mental health outcomes, no clear risk or protective factors were identified.

Summary of Functional/Social Outcome Results

We found 12 studies, all low quality, reporting functional/social outcomes for Veterans or members of the military with mTBI. Due to methodologic limitations as well as small sample size and inadequate reporting of and accounting for time since injury, the strength of evidence for this group of studies is low. One study reported that approximately 20% of Veterans with mTBI experience unemployment. One of two studies comparing participants with and without mTBI found higher unemployment among those with mTBI. Another study found that 26% of those with mTBI had difficulties with interpersonal relationships, though this was not significantly different in comparison to individuals without mTBI. Ten studies examined sleep disturbance: two found an overall prevalence of 13-23%, and seven found that sleep disturbances, when present, were moderate to severe. One of two studies found that sleep disturbance was more common in those with mTBI compared to those without. No clear patterns of risk or protective factors emerged from studies examining potential moderators of associations between mTBI and functional or social outcomes.

Summary of Service Utilization/Cost Results

We found seven low quality studies that described service utilization by those with mTBI, but no studies that reported costs associated with mTBI. The overall strength of evidence was low because of the small number and methodologic shortcomings of studies. The available literature suggests that there are few differences in service utilization for those with mTBI compared to similar controls; no significant associations with risk or protective factors were identified.


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, but it is not clear that those with mTBI experience more or higher severity symptoms than those without mTBI suggesting that outcomes may be influenced by other deployment-related conditions such as PTSD. The studies included in this report were low quality, cross sectional studies which did not provide consistent evidence for potential moderators of mTBI outcomes.


One of the major limitations of this literature is the inadequate reporting of and accounting for time since injury. 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 their analyses so that outcomes can be analyzed over time.

Few studies presented data on all outcomes of interest to the stakeholders of this review, and few studies reported their outcome reporting rationale. Most studies relied on clinical datasets, rather than research databases or registries. It is likely that many studies only included outcomes of relevance to the authors' particular study questions, though it is impossible to know whether some studies did not report outcomes given a lack of association with mTBI. There is a pressing need for large cohort studies of Veterans with and without mTBI that prospectively collect data on all 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.

Very few studies reported the actual prevalence of symptoms or conditions; most studies simply reported mean scores for the entire study group. Future research should report proportions of individuals with clinically significant impairment for each outcome.

Although a strength of this review was that many of the included studies relied on well-validated measures commonly used with Veteran/military populations, many of the clinical outcomes relied solely on self-reported symptoms, often obtained from single items on questionnaires. Results from this review and from the civilian literature suggest that self-reported deficits are more likely to be reported by individuals with mTBI compared to similar individuals without mTBI, particularly when associated with potential financial compensation. Future research should use objective and validated assessments, blinded outcome assessors, patient blinding to study hypotheses, and accounting for compensation factors whenever possible in order to reduce potential bias associated with outcome assessment. Additionally, future research should employ commonly used outcome assessment tools in order to facilitate the combination of results across studies for meta-analytic purposes.

A final strength of this review was the use of clear criteria for defining mTBI, as established by the VA and DoD. However, because the majority of studies did not assess or report imaging results, a key component of the VA/DoD criteria for mTBI, we were unable to use positive imaging results as an exclusion criteria. Future primary research should clearly report criteria used to define mTBI, including assessment and reporting of imaging results when available, and should consider examination of differences in outcomes based on definitional criteria for mTBI, as it is possible that less stringent criteria could be associated with different results.



American Congress of Rehabilitation Medicine


Air Force Base


Abbreviated Injury Scale


Army Medical Center


Automated Neuropsychological Assessment Metrics


Alteration of Consciousness/Mental State


Brooke Army Medical Center


Beck Depression Inventory 2nd Edition


Brief Traumatic Brain Injury Screen


Brief Visuospatial Memory Test Revised


Compensation and Pension


Clinician Administered PTSD Scale


Centers for Disease Control and Prevention


ANAM - code substitution delayed


ANAM - code substitution


Confidence Interval


Controlled Oral Word Association


Computed tomography


Chronic Traumatic Encephalopathy


Cleveland Veterans Affairs Medical Center


California Verbal Learning Test Second Edition


Dizziness Handicap Inventory


Delis-Kaplan Executive Function System Trail Making subtests


Department of Defense


Diffusion Tensor Imaging


Defense and Veterans Brain Injury Center


Dynamic Visual Acuity Test


Explosively Formed Projectile


Epworth Sleepiness Scale


Full Combat Exposure Scale


Frontal Systems Behavioral Scale


Estimated Full Scale IQ


General Educational Development


Glasgow Coma Scale


Hospital Anxiety and Depression Scale


Headache Impact Test-6


High School


Average days in ICU


Improvised explosive device


Interquartile range


Injury Severity Scale


Loss of consciousness


Length of stay


Military Acute Concussion Evaluation


Mild brain injury atypical symptoms scale


Migraine Disability Assessment Score


Mental Illness Research, Education and Clinical Center


Montreal Cognitive Assessment


Magnetic Resonance Imaging


ANAM - matching to sample


Mild traumatic brain injury


ANAM - mathematical processing


Motor vehicle accident


Not applicable


Not Reported


Neurobehavioral Symptom Inventory


Operation Enduring Freedom


Operation Iraqi Freedom


Operation New Dawn


Odds Ratio


PTSD Checklist


PTSD Checklist, Civilian version


PTSD Checklist, Military version


PTSD Checklist Stressor Specific Version


Postconcussive symptoms


Patient Health Questionnaire—15


Principal Investigator


Physical Medicine and Rehabilitation


Procedural reaction time


Physical training


Post-traumatic amnesia


Posttraumatic Stress Disorder


Repeatable Battery for the Assessment of Neuropsychological Status


Rey Complex Figure Test


Rey 15 Item test


Rey Osterlith Complex Figure Test


Rocket propelled grenade


Standardized assessment of concussion


Structured Clinical Interview for DSM-IV Axis I Disorders


Standard deviation


Systematic review


Simple reaction time


Traumatic brain injury


Test of Memory Malingering


Veterans Affairs Central Office


Veterans Affairs Medical Center


Vehicle borne improvised explosive device


Veterans Health Administration


Veterans Integrated Service Network


Victoria Symptom Validity Test


Wechsler Adult Intelligence Scale Third Edition


Wechsler Adult Intelligence Scale Version IV


Wechsler Abbreviated Scale of Intelligence


World Health Organization


Wechsler Memory Scale Third Edition


Walter Reed Army Medical Center


Wechsler Test of Adult Reading

Cover of Complications of Mild Traumatic Brain Injury in Veterans and Military Personnel: A Systematic Review
Complications of Mild Traumatic Brain Injury in Veterans and Military Personnel: A Systematic Review [Internet].
O'Neil ME, Carlson K, Storzbach D, et al.
Washington (DC): Department of Veterans Affairs (US); 2013 Jan.

PubMed Health Blog...

read all...

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...