Repeated blast exposures may harm the brain health of military personnel

The brains of special warfare community personnel repeatedly exposed to blasts show increased inflammation and structural changes compared with a control group, potentially increasing the risk of long-term, brain-related disease, according to a new study.

Researchers from the University of Virginia School of Medicine and Naval Medical Research Command (NMRC) led the study, which compared the brains of nine special operations personnel exposed to blasts with a control group of nine military service members with only minimal exposures to blasts. Participants’ brains were analyzed using sophisticated imaging techniques, combined with surveys that measured exposure to weapons and explosives as well as symptoms related to brain injury, including mood and sleep issues.

The study found that increased blast exposure was associated with increased brain inflammation, and reduced volume and thickness of brain structures. This could affect several key brain functions, including memory, motor skills and regulating emotions.

Previous studies have shown that people with many neurodegenerative conditions – including Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis (ALS) – all have chronic brain inflammation that may be detectable before the conditions fully develop.

“This is the first study to directly demonstrate increased inflammation in the brains of service members who are exposed to small blasts over a career,” said James Stone, MD, PhD, a UVA Health radiologist who led the study. “Brain inflammation is such a key process in other brain-related illnesses. These findings raise concerns about the long-term brain health of those exposed to repeated low-level blasts.”

Better Protecting Military Personnel

The next step for researchers is a larger study with more participants to determine precisely what levels of blast exposure cause brain injuries. This next study could guide military leaders in how they deploy soldiers as well as improve the design of equipment to protect against brain injuries caused by repeated blasts.

“Work is currently underway to better understand these findings and to be able to answer the question of ‘how much is too much?’ when it comes to blast overpressure exposure,” Stone said. 

The study is one of several projects involving UVA Health researchers seeking to prevent brain injuries in military personnel led by Stephen Ahlers, PhD, from NMRC. UVA is part of a research team backed by an $8 million U.S. Department of Defense grant exploring the role of brain inflammation in military personnel exposed to blast shock waves. 

“This research effort will enable us to understand how repetitive exposure to blast over a career is a risk factor for brain health issues, including the possibility of worsening symptoms from a traumatic brain injury unrelated to blast exposure,” according to Ahlers. 

UVA researchers are also part of a group developing a model to predict how regular exposure to artillery blasts affects the brains of military personnel.

Findings Published

The researchers published their findings in the Journal of Neurotrauma. The research team consisted of Brian B. Avants, Nicholas Tustison, Jessica Gill, Elisabeth A. Wilde, Kiel D. Neumann, Leslie A. Gladney, Madison O. Kilgore, F. Bowling, Christopher M. Wilson, John F. Detro, Heather Belanger, Katryna Deary, Hans Linsenbardt, Ahlers and Stone.

This work was supported and funded by the Department of Defense Military Operational Medicine Research Program.

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