Traumatic Brain Injury and Veteran Mortality After the War in Afghanistan

On August 30, 2021, the last US military service members left Afghanistan, marking the end of America’s longest war. It is important to continue to examine the impact of the war on service members, veterans, family members, clinicians, and health care systems. Traumatic brain injuries (TBIs) are often described as one of the signature injuries of the war. Estimates of TBI among service members who have returned from military operations in Iraq and Afghanistan vary moderately, which highlights the critical importance of TBI definitions and methods to ascertain TBI exposure. Estimates suggest that between 9% and 28% of service members experienced a TBI.¹ Complicating matters further, many veterans experienced 1 or more TBIs before their military service, thereby suggesting that military-related injuries may be neither the first nor the worst lifetime injury sustained. Regardless of the true prevalence of TBI, it is clear that TBI represents a major health care issue for veterans. Additional research is needed to understand the long-term health outcomes for veterans with TBIs. The results should guide clinical, research, and policy-based decisions.

Within this context, the analyses by Howard and colleagues² represent a timely contribution examining the association of TBI severity with mortality among more than 2.5 million veterans serving after September 11, 2001 (9/11). These secondary analyses were conducted as part of a larger study designed to examine health trajectories over time. Therefore, Howard et al² were right to highlight their limitations; this was not a population-based cohort study of all post-9/11 TBI cases. Cases were required to have 3 or more years of Department of Defense (DoD) health care, and 2 or more years of Veterans Health Administration (VHA) care for those who entered the VHA; therefore, these results should be confirmed in future studies. The authors found that all-cause mortality was higher among post-9/11 military veterans compared with the general population, and the differences increased along with TBI severity, especially among older veterans.² Different patterns emerged when external causes of death (ie, accidents, suicide, and homicides), cancer, and cardiovascular disease were examined separately; rates of external causes of death were especially high among those with a moderate-to-severe TBI. The authors calculated excess death estimates. Although only 3% of the post-9/11 cohort had a moderate-to-severe TBI, they accounted for 33.6% of total excess deaths.²

The study by Howard et al² highlights challenges identified early in the war as TBI evolved as a critical issue. How should TBI be defined? What methods should be used to ascertain TBI cases? Despite substantial progress on these issues, many researchers are forced to make trade-off decisions that balance feasibility with reference standard methods. These methodological issues create challenges for identifying the true rate of TBI, injury severity, and short- and long-term outcomes associated with such injuries (eg, mortality and cause of death). In this study,² TBI cases were identified at least in part with TBI screening procedures for deployment-related injuries. Challenges and limitation associated with VHA and DoD screening procedures have been previously discussed³ and should be considered in the interpretation of the results. Without substantial and coordinated efforts, challenges with screening and diagnostic definitions are expected to persist. Efforts to refine diagnostic definitions for TBI, as well as future signature injuries, should be prioritized. This will facilitate valid and reliable case identification and advance the development of interventions to help service members and veterans.

The findings presented by Howard and colleagues² are relatively consistent with previously published literature. History of TBI (all levels of severity) is associated with both mood-related symptoms (eg, depression), as well as new or exacerbated psychiatric conditions (eg, posttraumatic stress disorder). In addition, those with TBI and, in particular, more severe injury often cope with secondary health conditions (eg, obesity, chronic pain) that are known to be related to increased risk for conditions associated with mortality. For example, Harrison-Felix and colleagues⁴ found that those who received civilian inpatient rehabilitation for TBI were 1.5 times more likely to die than members of the general population and had an estimated average life expectancy reduction of 4 years. Rates of death secondary to suicide, aspiration pneumonia, other pneumonias, digestive conditions, and seizures were greater than expected.

Howard and colleagues² reported higher all-cause mortality among post-9/11 veterans compared with members of the US population. Although the differences increased with TBI severity, this was true for the total cohort, and the no-TBI group as well. This finding adds to literature that suggests that the post-9/11 cohort substantially differs from prior military cohorts. Historically, military populations have generally had lower mortality rates than the general population. This so-called healthy worker effect has often been attributed to military screening and selection procedures, access to health care, and other military characteristics (eg, routine exercise). The data reported by Howard et al² still include evidence for a healthy worker effect, but results differ by the specific cause of death. There were lower rates of mortality due to cardiovascular disease and all other causes compared with the general population; higher rates of mortality were primarily observed among external causes of death. It is also worth noting that without a draft, a small number of individuals bore the burden of these conflicts (eg, multiple deployments). This fact in itself is substantially different than previous conflicts and would be expected to affect physical and mental health outcomes.

There were early signs during the wars in Iraq and Afghanistan that some atypical mortality patterns were evolving. For example, the US Army suicide rate almost doubled from 2005 to 2011.⁵ Prior research during the last century suggested that Army suicide rates actually declined during times of war.⁶ Although many have speculated about the reasons for the high military suicide rates in the last 20 years, simple answers have been elusive and the reasons for the high rates remain largely unknown.

The findings of Howard et al² continue to highlight the importance of suicide prevention among post-9/11 veterans. Suicide had the highest number of excess deaths. They estimated that there were 4219 excess deaths due to suicide (1437 among those exposed to TBI).² Prior research suggests that even mild TBI is associated with a 2-fold higher risk of suicide.⁷ Prevention is challenging because many suicidal veterans with a history of TBI may not be receiving mental health services. To address this and similar challenges, the VHA instituted the largest population-based suicide risk screening program in the country (VA Risk ID).⁸ One of the goals is to increase screening in non–mental health settings, where research suggests many individuals receive care shortly before a suicide.

With the end of the war in Afghanistan, it is important to apply the lessons learned. Service members survived more severe injuries compared with prior wars, and they will need support for many years to come. Research has advanced our definitions of concussion and TBI, identified target mechanisms and consequences of TBI, contributed to the development of new screening tools and interventions, and facilitated the creation of national guidelines for clinical care. However, challenges remain. VHA and DoD clinical practice guidelines on the management and rehabilitation of post-acute mild TBI note limited evidence for the management of a range of symptoms and co-occurring conditions associated with TBI (eg, cognitive deficits, sleep disturbance, visual deficits, depression, suicidality, alcohol use disorder, and posttraumatic stress disorder).⁹ Treatment development is still needed to address the wide range of needs for veterans with TBI, including mental health, memory and executive functioning deficits, physical well-being, and social support.

Published: February 11, 2022. doi:10.1001/jamanetworkopen.2021.48158

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Reger MA et al. JAMA Network Open.

Corresponding Author: Mark A. Reger, PhD, Veterans Affairs Puget Sound Health Care System, 1660 S Columbian Way, S-116, Seattle, WA 98108-1532 (mark.reger@va.gov).

Conflict of Interest Disclosures: Dr Reger reported that this work was conducted as a part of federal employment in the Department of Veterans Affairs during the conduct of the study. Dr Brenner reported consulting with sports leagues via her university affiliation. No other disclosures were reported.

Disclaimer: The views expressed are those of the authors and do not reflect the official policy or position of the US Department of Defense, US Department of Veterans Affairs, or the US government.