A new study provides evidence that military personnel in occupations that expose them to blast waves are more likely to have medical records showing problems with anger, aggression, or violence. The findings, published in the journal Military Medicine, suggest that the physical effects of routine explosions may contribute to long-term behavioral challenges. This association is evident even when other mental health factors, such as post-traumatic stress disorder, are taken into account.
Routine military missions often involve exposure to low-level blast waves. These frequently occur during weapons training, explosive breakthroughs, and active combat. Over time, these repeated shock waves cause what scientists call military occupation blasts and impulse exposures.
Although these explosions are often not powerful enough to cause an immediate concussion, the cumulative effects of repeated pressure waves can affect the human body. Recent attention has focused on how this particular type of repeated physical trauma affects long-term neurological and psychological health. The precise biological effects of low-level explosions are an active area of scientific research.
Anger, aggression, and violence are significant clinical concerns that can lead to interpersonal conflict, psychological distress, and self-harm. Military personnel tend to have more difficulty controlling their anger than the general public. Identifying modifiable risk factors for these behaviors is a priority for veterans health care.
Previous studies examining the relationship between exposure to explosions and aggressive behavior have often relied on self-report surveys or small groups of participants. These methods have made it difficult to separate the specific effects of routine blast exposure from other complex military experiences. Small sample sizes also limit the statistical power needed to spot subtle behavioral trends.
To overcome these data collection challenges, researchers utilized the latest in artificial intelligence. By using advanced text analysis of medical records, scientists aimed to accurately detect subtle references to aggressive behavior in vast amounts of clinical data. This approach allowed the research team to estimate the association between occupational blast exposure and problem behavior on a larger scale.
Researchers analyzed data from a large number of veterans who received care from both the Department of Defense and the Veterans Health Administration. Within this broader population, they identified a group of 5,000 military occupation veterans who were at high risk of exposure to blast waves. These high-risk roles include artillery, special operations forces, combat engineers, weapons training instructors, and more.
This high-risk group was then matched with a control group of 5,000 veterans with no history of high-risk occupational blast exposure. A matching process ensured that both groups were comparable in terms of age, gender, race, and ethnicity. The study sample included a total of 10,000 veterans.
To find evidence of anger, aggression, and violence, the research team analyzed 3.64 million clinical text notes from veterans’ medical records. Since it is physically impossible for humans to review millions of documents, the researchers employed large-scale language models and natural language processing. These are advanced artificial intelligence tools designed to read, understand, and classify human text based on context.
A 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 decisions, the scientists manually reviewed 1,000 notes and compared the human ratings with the artificial intelligence’s predictions. The software achieved 96% accuracy during this testing phase.
After processing all the medical records, the researchers categorized the veterans based on the concentration of behavioral problems in their files. Veterans were considered to have anger, aggression, or violence problems if at least 5% of their clinical notes contained relevant content. Interestingly, anger was relatively rare across the study sample. Less than 3 percent of all clinical notes analyzed mentioned anger, aggression, or violence.
The analysis revealed that veterans who worked in jobs that exposed them to blast waves were significantly more likely to have a clinical record of behavioral problems. In raw numbers, 17.2 percent of the high-risk blast exposure group met criteria for anger, aggression, or violence issues. In contrast, only 12.0% of the control group met the same criteria.
The researchers also used statistical models to adjust for other factors that may influence aggressive behavior. These took into account age, gender, combat exposure, number of deployments, and various medical conditions. Medical conditions considered included traumatic brain injury, substance use disorders, and other physical illnesses common among military personnel.
Even after controlling for these variables, the association between high-explosion-risk occupations and aggressive behavior remained statistically significant. Veterans in high-explosive roles were 22 percent more likely to have anger and aggression recorded in their medical files than those in low-explosive roles.
“Although the effects were modest, our findings suggest that long-term exposure to occupational blasts is a risk factor for anger, even when unrelated to other military exposures,” says Eamon Kennedy, assistant professor of epidemiology research at the University of Utah Health and health sciences research specialist at the VA Salt Lake City Healthcare System. Kennedy is the study’s lead author.
The data highlighted several other factors associated with behavioral problems. Both experiencing a traumatic brain injury and exposure to combat predicted increased rates of anger and violence. Being female or older tends to act as a protective factor, correlating with lower odds of these behavioral markers.
Post-traumatic stress disorder (PTSD) has emerged as a highly relevant factor. When the researchers factored PTSD into their most complex statistical models, the specific effect size of blast exposure was reduced, although it remained statistically significant. The authors noted that this makes sense because anger is a core symptom of PTSD, and veterans who worked in high-blast occupations naturally have higher rates of the disorder.
This finding suggests that there is not a single, isolated cause of behavioral change, but rather a complex web of overlapping military experiences. “Occupational exposure to low-level explosions exists within a network of many interacting exposures and risks, including stress, trauma, physical injury, and mental illness,” Kennedy says. “However, for those experiencing hardship, occupational blast exposure can pose an additional burden.”
One of the major limitations of this study is that estimates of blast exposure rely on military occupational regulations. This means that although researchers were able to identify individuals who worked in high-risk jobs, they were unable to measure the exact number or intensity of explosions that individual veterans actually experienced.
Another limitation is that anger, aggression, and violence are often underreported by patients and underreported by health care providers. The actual prevalence of these behavioral problems may be higher than the estimates because the artificial intelligence only searched existing medical records. Healthcare professionals may also use different words for different patients when documenting behavioral problems.
Future research could benefit from tracking more precisely how many explosions soldiers endure during their lifetimes. Distinguishing between personnel with minimal exposure and those with extensive and repeated exposure may help elucidate the biological mechanisms at play. Detailed exposure tracking devices similar to radiation badges used in other fields could provide a path to collecting accurate data.
Scientists are currently exploring several possible biological explanations for how explosions affect the brain. Repeated pressure waves can cause microscopic damage to the brain’s wiring, cause chronic brain inflammation, and destroy blood vessels in the brain. Some researchers are studying how blast shock waves affect the gut-brain axis, highlighting the need to view everyday explosive exposure as a systemic health issue.
Recognizing occupational blast exposure as a predictable and modifiable risk factor can lead to better safety protocols. Introducing stricter standoff distances during weapons training and tracking cumulative blast exposure could help reduce long-term behavioral effects on service members.
“Occupational blast exposure is mostly modifiable because it usually occurs during training in very controlled conditions, so the harm can be reduced,” Kennedy says. “There is a balance between ensuring that people are trained and prepared to perform their duties, but with less risk of adverse health effects.”
The study, “When the fuse is lit: The link between anger, aggression, and violence in military career detonation,” was authored by Eamonn Kennedy, Shashank Badramani, Megan Amouan, Ian J. Stewart, Shannon R. Miles, Sarah L. Martindale, Lisa A. Brenner, and Mary Jo Pugh.
