Over 2,500 U.S. service members have been killed by improvised explosive devices (IEDs) in Iraq and Afghanistan since 2001, and over 20,000 more have been injured. A new study has revealed that IED blasts leave lasting signatures on the brains of combat veterans who survive the attack. The regions of the brain most effected by the blast control memory, decision making, and reasoning. Vassilis Koliatsos from the Johns Hopkins University School of Medicine is senior author of the paper, which was published in Acta Neuropathologica Communications.
During World War I, many soldiers who had been subjected to constant bombardment on the front lines suffered from what was then known as ‘shell shock’: a disorder which manifested as a variety of psychological conditions that were never fully explained. While the term ‘shell shock’ is no longer used in favor of more descriptive diagnoses, today’s combat troops face similar blast stresses from IEDs, mortar fire, rocket propelled grenades, car bombs, and suicide bombers. Koliatsos and his team sought to understand the extent of the damage these explosions leave.
"This is the first time the tools of modern pathology have been used to look at a 100-year-old problem: the lingering effect of blasts on the brain," Koliatsos said in a press release. "We identified a pattern of tiny wounds, or lesions, that we think may be the signature of blast injury. The location and extent of these lesions may help explain why some veterans who survive IED attacks have problems putting their lives back together.”
In order to find out how an IED blast compared to other types of neurotrauma, the team obtained the brains of five male combat veterans who had survived IED attacks but later died from unrelated causes. The bodies had been donated to the Armed Forces Institute of Pathology. These were compared to the brains of 24 other individuals who had died from other reasons, including heart attacks and car crashes.
(Left) Lesions of a brain involved in a car crash (Center) Lesions from IED blast injury (Right) Lesions from drug overdose. Image credit: Vassilis Koliatsos
The brains were treated with a biomarker which causes swelling where there are breaks in the neurons. Four of the troops who had survived IED blasts produced honeycomb-shaped swelling, distinct from any other cause of death analyzed in the study. While there weren’t signs of concussion in the brain, there were signs of brain inflammation.
These areas with damaged neurons were found in many areas of the brain including the frontal lobe; responsible for executive functions such as memory, speech, and decision making. It was not clear, however, if the damage was caused by the blast, or if the explosion compromised the neurons and made them more susceptible to damage from other causes.
”When you look at a brain, you are looking at the life history of an individual, who may have a history of blasts, fighting, substance abuse or all of those," Koliatsos explained. "If researchers could study survivors' brains at different times after a blast—a week, a month, six months, one year, three years—that would be a significant step forward in figuring out what actually happens over time after a blast.”
Troops coming home from war often experience PTSD, depression, anxiety, and other psychological disorders, which could be playing a role in the number of veteran suicides. Having a better understanding of the physical damage caused by IEDs could lead to new treatments for these individuals, improving their quality of life.