The conflicts in Iraq and Afghanistan significantly increased recognition of traumatic brain injury (TBI) among military personnel, particularly mild and sub-concussive injuries associated with blast exposure. Despite this awareness, accurately quantifying deployment-related TBI remains challenging. Most published estimates rely on self-reported symptoms, retrospective surveys, or extrapolated administrative data, reflecting the absence of objective, field-deployable diagnostic tools. Consequently, uncertainty persists regarding the true incidence, severity, and cumulative burden of TBIs sustained during deployment, including the prevalence of multiple or repetitive injuries¹,².
This diagnostic gap highlights a critical operational need for rapid, objective methods capable of assessing brain injury at or near the point of exposure, including in battlefield and training environments.
Large-scale surveys illustrate the scale of the issue but also its limitations. The RAND Corporation’s Invisible Wounds of War study, conducted between 2007 and 2008, surveyed 1,965 previously deployed U.S. service members and reported that approximately 19–20% met criteria for a “probable TBI”, largely based on self-reported exposure and symptoms³. Extrapolated across the deployed force at the time, this corresponded to more than 300,000 service members potentially affected. However, contemporaneous Department of Defense surveillance data indicated that substantially fewer cases had been formally diagnosed, reflecting under-recognition and diagnostic uncertainty⁴.
More recent analyses confirm that mild and repetitive TBIs remain under-detected, despite improved screening and awareness. The Defense and Veterans Brain Injury Center (DVBIC) reports that hundreds of thousands of TBIs have been documented among U.S. service members since 2000, with over 80% classified as mild, yet acknowledges ongoing limitations in objective injury confirmation and severity stratification⁵. These challenges continue to impede accurate epidemiology, clinical decision-making, and long-term force health management.
Due to the inherent complexity of modern warfare and the clinical heterogeneity of traumatic brain injury (TBI), accurately determining injury severity and the incidence of multiple or repetitive TBIs among service members remains challenging. The principal limitation continues to be the absence of an objective, field-deployable method to confirm brain injury. Operational environments, polytrauma, stress, fatigue, and delayed presentation further complicate assessment, particularly for mild and subconcussive injuries⁶,⁷.
In response to this gap, the Military Acute Concussion Evaluation (MACE) was introduced in 2006 as a frontline screening tool. While MACE has been widely adopted and remains an important component of military medical protocols, its limitations are well recognised. The assessment relies heavily on subjective symptom reporting and recall, is influenced by fatigue and stress (similar to other neurocognitive tests), and demonstrates reduced sensitivity when administered more than 12–24 hours after injury⁸,⁹. Importantly, MACE does not provide biological confirmation of injury and is vulnerable to confounding factors common in combat settings, including extracranial injury and operational stress. As a result, a substantial diagnostic gap persists for an objective method that is resilient to battlefield conditions.
Diagnosing TBI—particularly in the presence of comorbid conditions such as post-traumatic stress disorder (PTSD), depression, and sleep disturbance—remains complex. At present, no single screening instrument provides a definitive diagnosis of TBI. The diagnostic gold standard remains a comprehensive clinical assessment by an experienced clinician, often requiring longitudinal follow-up⁷. Even current U.S. Department of Veterans Affairs (VA) screening tools are intended only to identify individuals who require further evaluation, rather than to confirm injury⁶.
The financial burden associated with deployment-related brain injury and comorbid psychological conditions is substantial. Among U.S. service members deployed since 2001, PTSD and major depression alone have been estimated to cost USD $4–6 billion within the first two years following deployment, driven by healthcare utilisation, lost productivity, and disability compensation¹⁰. TBI adds significantly to this burden. The Defense and Veterans Brain Injury Center (DVBIC) reports that over 490,000 TBIs have been diagnosed among U.S. service members since 2000, with more than 80% classified as mild¹¹. While precise cost-per-case estimates vary, analyses consistently demonstrate that even mild TBI contributes disproportionately to long-term healthcare costs, particularly when injuries are repetitive or inadequately identified early⁶,¹¹.