Researchers have discovered honeycomb-shaped patterns of broken and swollen nerve fibers in the brains of some veterans who survived an improvised explosive device (IED), according to a new study at Johns Hopkins University.
These hidden brain injuries may be the physical evidence behind the notorious “shell shock,” an array of cognitive and psychological difficulties.
Doctors treating IED survivors “often see depression, anxiety, post-traumatic stress, and substance abuse or adjustment disorders. Life is very difficult for some of these veterans,” said senior author Vassilis Koliatsos, M.D., a professor of pathology, neurology, and psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.
“It’s important to understand that at least a portion of these difficulties may have a neurological foundation.”
“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.”
Soldiers have been suffering from bomb-induced brain damage since World War I, when German and Allied forces tried to blast one another out of the trenches. Many World War I fighters survived the combat apparently unscarred, but suffered from terrible psychological difficulties known as shell shock.
After World War I, mass bombardments of troops were less common, and shell shock became more rare. Shell shock, now renamed blast neurotrauma or blast injury to brain, has re-emerged due to insurgent forces’ widespread use of IEDs in Iraq and Afghanistan.
For the study, the researchers examined the brains of five male United States military veterans who survived IED attacks but later died. Their remains had been donated to the Armed Forces Institute of Pathology.
Three died of methadone overdoses that could have been accidental, Koliatsos says, since the drug is often prescribed for soldiers’ chronic pain. One died of a gunshot wound to the head, and one died of multiple organ failure.
The scientists compared the veterans’ brains to those of 24 people who died of a range of causes, including motor vehicle crashes, opiate overdoses and heart attacks.
“In brains that had been exposed to blasts, we see microglial cells right next to these unusual axonal abnormalities,” Koliatsos said. Brain inflammation develops slowly, so microglia don’t typically appear in drug overdose cases. Their presence suggests the veterans who overdosed had pre-existing brain injuries.
The researchers found these lesions in several brain regions, including the frontal lobes, which control decision making, memory, reasoning and other executive functions.
The lesions may be fragments of nerve fibers that broke at the time of the blast and slowly deteriorated, or they may have been weakened by the blast and broken by some later injury like a concussion or drug overdose.
“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 says.
“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.”
The study is published in the journal Acta Neuropathologica Communications.
Source: Johns Hopkins Medicine