New research provides evidence that military personnel working in occupations with high exposure to blasts are more likely to have medical records indicating issues with anger, aggression, or violence. Published in the journal Military Medicine, the findings suggest that the physical impacts of routine explosive blasts may contribute to long-term behavioral challenges. This association remains visible even when accounting for other mental health factors like post-traumatic stress disorder.
Routine military duties often involve exposure to low-level blasts. These occur frequently during weapons training, explosive breaching, and active combat. Over time, these repeated shockwaves create what scientists call military occupational blast and impulse exposure.
While these blasts are often not strong enough to cause an immediate concussion, the cumulative effect of these repeated pressure waves can impact the human body. Recent attention has focused on how this specific type of repeated physical trauma might affect long-term neurological and psychological health. The exact biological impact of low-level blasts is an active area of scientific inquiry.
Anger, aggression, and violence are significant clinical concerns that can lead to interpersonal conflict, psychological distress, and self-harm. In military populations, difficulties with managing anger tend to be more common than in the general public. Identifying modifiable risk factors for these behaviors is a priority for veterans’ healthcare.
Previous studies examining the relationship between blast exposure and aggressive behavior often relied on self-reported surveys or small groups of participants. These methods made it difficult to isolate the specific effects of routine blast exposure from other complex military experiences. Small sample sizes also limit the statistical power needed to find subtle behavioral trends.
To overcome these data collection challenges, researchers utilized modern artificial intelligence. By using advanced text analysis on medical records, the scientists aimed to accurately detect subtle mentions of aggressive behavior across a massive amount of clinical data. This approach allowed the research team to estimate the association between occupational blast exposure and behavioral issues on a much larger scale.
The researchers analyzed data from a large population of veterans who received care from both the Department of Defense and the Veterans Health Administration. From this wider population, they identified a cohort of 5,000 veterans who had served in military occupations with a high risk for blast exposure. These high-risk roles included artillery, special operations forces, combat engineers, and weapons training instructors.
This high-risk group was then matched with a control group of 5,000 veterans who had no history of high-risk occupational blast exposure. The matching process ensured that both groups were comparable in terms of age, sex, race, and ethnicity. In total, the study sample included 10,000 veterans.
To find evidence of anger, aggression, or violence, the research team analyzed 3.64 million clinical text notes from the veterans’ medical records. Because human review of millions of documents is physically impossible, the researchers employed large language models and natural language processing. These are sophisticated artificial intelligence tools designed to read, understand, and categorize human text based on context.
The secure, offline artificial intelligence pipeline was trained to look for specific phrases and concepts related to anger management, explosive outbursts, difficulties with self-control, and known anger triggers. To ensure the computer program was making accurate judgments, the scientists manually reviewed 1,000 notes and compared their human assessments against the artificial intelligence predictions. The software achieved a 96 percent accuracy rate during this testing phase.
After processing all the medical notes, the researchers categorized veterans based on the concentration of behavioral issues in their files. A veteran was considered to have an issue with anger, aggression, or violence if at least five percent of their clinical notes contained related content. Interestingly, anger was relatively rare across the entire study sample. Less than three percent of all clinical notes analyzed mentioned anger, aggression, or violence.
The analysis revealed that veterans in occupations with high blast exposure were significantly more likely to have clinical notes indicating behavioral problems. In raw numbers, 17.2 percent of the high-risk blast exposure group met the criteria for issues with anger, aggression, or violence. In comparison, only 12.0 percent of the matched control group met the same criteria.
The researchers also used statistical models to adjust for other factors that might influence aggressive behavior. They accounted for age, sex, combat exposure, number of deployments, and various medical conditions. Medical conditions considered included traumatic brain injury, substance use disorders, and other physical ailments common in military populations.
Even after adjusting for these variables, the association between high-risk blast occupations and aggressive behavior remained statistically significant. Veterans in high-blast roles had 22 percent higher odds of having anger or aggression documented in their medical files compared to those in low-blast roles.
“Although the effect was moderate, our findings do suggest that long-term occupational blast exposure is a risk factor for anger, even independently of other military exposures,” says Eamonn Kennedy, a research assistant professor of epidemiology at University of Utah Health and a research health science specialist at the VA Salt Lake City Health Care System. Kennedy is the first author of the study.
The data highlighted several other factors associated with behavioral issues. Experiencing a traumatic brain injury and having combat exposure both predicted higher rates of anger and violence. Being female or being older tended to act as protective factors, correlating with a lower likelihood of these behavioral markers.
Post-traumatic stress disorder, or PTSD, emerged as a highly relevant factor. When the researchers factored PTSD into their most complex statistical models, the specific effect size of blast exposure shrank, though it remained statistically significant. The authors noted that this makes sense because anger is a core symptom of PTSD, and veterans in high-blast occupations naturally had elevated rates of the disorder.
The findings suggest a complex web of overlapping military experiences rather than a single, isolated cause for behavioral changes. “Occupational exposure to low-level blasts exists within a network of numerous interplaying exposures and risks, stress, trauma, physical injury, psychiatric illness, and so on,” Kennedy says. “But for people who are experiencing challenges, occupational blast exposure can be an additional burden.”
One major limitation of the study is that it relies on military occupational codes to estimate blast exposure. This means the researchers could identify who worked in high-risk jobs, but they could not measure the exact number or intensity of blasts any individual veteran actually experienced.
Another limitation is that anger, aggression, and violence are often underreported by patients and under-documented by healthcare providers. Because the artificial intelligence only searched existing medical notes, the true prevalence of these behavioral issues might be higher than the estimates provide. It is also possible that providers use different language for different patients when documenting behavioral issues.
Future research could benefit from more precise tracking of how many blasts service members endure over their careers. Differentiating between personnel with minimal exposure and those with extensive, repeated exposure could help clarify the biological mechanisms at play. Detailed exposure tracking devices, similar to radiation badges used in other fields, might offer a path forward for gathering exact data.
Scientists are currently exploring several potential biological explanations for how blasts affect the brain. Repeated pressure waves might cause microscopic damage to brain wiring, trigger chronic brain inflammation, or disrupt blood vessels in the brain. Some researchers are even investigating how blast shockwaves might affect the gut-brain axis, highlighting the need to view routine explosive exposure as a whole-body health issue.
Recognizing occupational blast exposure as a predictable and modifiable risk factor could lead to better safety protocols. Implementing stricter stand-off distances during weapons training and tracking cumulative blast exposure could help reduce the long-term behavioral consequences for military personnel.
“Occupational blast exposure is largely modifiable because it typically occurs during training, where we have very, very controlled situations, and that gives us access for reducing harm,” Kennedy says. “There’s a balance where people can still be trained and prepared to do the mission, but with less risk for these negative health consequences.”
The study, “When the Fuse Is Lit: Association of Military Occupational Blast Exposure With Anger, Aggression, and Violence,” was authored by Eamonn Kennedy, Shashank Vadlamani, Megan Amuan, Ian J. Stewart, Shannon R. Miles, Sarah L. Martindale, Lisa A. Brenner, and Mary Jo Pugh.