Finding ways to model those effects can be difficult but could lead to new insights into treatment and even prevention, researchers at Georgia Regents University said.
The Institute of Medicine provided an extensive look at blast injuries as part of a congressionally mandated series of reports on military injuries dating back to the Persian Gulf War. In the conflicts in Iraq and Afghanistan, where 6,700 service members were killed and 50,500 were wounded, the vast majority were caused by explosions, according to the report.
Improvised explosive devices accounted for 75 percent of all injuries, the report said. Advances in treatment and personal protection led to a big increase in survivors: the ratio of wounded to dead grew from 3.2 survivors per death in the Persian Gulf War to 9.7 per death in the latest conflict, according to the report.
“We’ve been very effective in creating better personal protective equipment,” said Dr. John Vender, a neurosurgeon at GRU and a researcher into brain and blast injuries.
When taking into account brain injuries, that wounded ratio would be even higher. More than 240,000 brain injuries were reported in Afghanistan and Iraq, and the vast majority – 187,000 – would be considered mild traumatic brain injuries.
That doesn’t mean the long-term effects are mild, GRU researchers said. For instance, the injuries can frequently disrupt hormonal systems in the body, leading to common symptoms such as depression that can be hard to tease out, Vender said.
“Depression is sometimes a final common pathway of the injury; it is sometimes a response to injury,” he said. “You can see depression coming from different directions.”
Recently, the GRU team turned up evidence that the injuries can also disrupt the circadian rhythm in the body, said Kris Dhandapani, a neuroscientist who works with Vender on trauma research.
“Sleep/wake rhythms seem to be disrupted,” he said.
The effects are likely caused by a cascade of events within the body, Vender said.
“We understand now more than ever that nothing works in our body in isolation,” he said. “Every single event, every single trauma that is going to disrupt any normally functioning system” has effects on other systems.
More understanding is needed to know whether the body’s response to those disruptions is part of the solution or part of the problem, Dhandapani said. For instance, researchers used to believe there was little interaction between the immune system and the brain and other parts of the nervous system, but they now know that is not true, he said.
“Now what we’re seeing is they are talking to one another, they are sending hormone signals,” Dhandapani said.
There is a massive immune response after brain trauma, and that elevated response has been shown to persist in some cases 17 years later. Whether it is a help or not is the question, he said. It could be that an immune response is helpful the first day but harmful if it persists days later, or vice versa, he said.
The GRU researchers have had their most success in trying to prevent damage from trauma by pretreating with chemicals that might limit the damage. Vender and Dhandapani are co-investigators on a research project looking at using the common food dye Brilliant Blue G to limit brain damage.
Not everyone can be pretreated, but those at high risk, such as soldiers heading into battle or police officers and firefighters, could be if the right pretreatment is found, Vender said.
“It needs to be relatively side-effect- or symptom-free because most people aren’t going to take a medication that turns them blue,” he said, as happens with mice who are fed the Brilliant Blue G dye.
Certain people might be more at risk of greater damage regardless of profession, Dhandapani said.
“There seems to be a genetic component to it,” he said. “Whether that would apply to the people Dr. Vender would see, I think that is up in the air still.”
There is a greater need for this in the civilian world too, and certainly in places such as the NFL, Vender said.
“A lot of people suffer repetitive mild injuries or mild to moderate injuries,” he said.
Being able to use specially bred mice, where certain genes can be turned on and off in different systems in the body, could help researchers understand this better on a fundamental level, Dhandapani said.
“Then we can start targeting, going looking for those drugs or gene therapies, whatever it may be, to hopefully help these patients long-term,” he said.