What battlefield explosions do to the brain

_{Illustration: Patty Alvarez}

Military doctors consider traumatic brain injury the “signature wound” of the conflicts in Iraq and Afghanistan, where soldiers were repeatedly exposed to shockwaves from battlefield explosions. Now a study from Leidos and the U.S. Navy finds veterans reported more symptoms following shockwave exposure than blunt trauma to the head.

Why you should know: Understanding the differences between these types of concussions, and understanding how to better treat them, is viewed as a major step in easing the military’s mental health crisis.

From the source: “The problem is we don’t have a nuanced understanding of how damage to the brain might be different in concussions that result from blast exposure compared to blunt trauma,” said Dr. Jennifer Belding, who was the study’s lead scientist. “It’s a growing area of research, but some of our biggest questions might take years to answer.”

Specifics: High-level blast exposure might result from detonated land mines, grenades, or improvised explosive devices (IED). However, Dr. Belding’s research studied low-level blast exposure that results from smaller explosions from breaching doors or firing artillery, for example. Regardless of its size, every explosion creates pressure waves that move outward at a rapid pace, and exposure to them may cause damage to the brain.

Zooming out: The study is part of a 2018 congressional mandate requiring longitudinal analysis of blast exposure. In 2019, Congress further directed the Pentagon to include blast exposure in military medical records which are needed to better screen, mitigate, and treat adverse health outcomes.

Looking ahead: Treating traumatic brain injury is one of the military’s top priorities, but the advancement of medical knowledge requires the observation of patients over time. Belding said research in this area is progressing rapidly, but there’s a lot more to understand, including the specific injury mechanism that results from blast exposure. How do pressure waves directly translate to cognitive defects? Because the brain is the most complex organ in the body, it could take years to answer this question.

The data says: The military reported more than 400,000 brain injuries between 2000-2019, most of which were mild concussions. According to the U.S. Department of Veterans Affairs (VA), roughly 22% of all combat casualties from Iraq and Afghanistan involved brain injuries. Other research suggests thousands more brain injuries in the military have gone undiagnosed during this time.

Final word: Brain injury from blast exposure is an occupational hazard for many soldiers. We owe it to them to better understand this so-called invisible wound of war, which can take years to surface and heal.