Most concussions are due to physical forces that occur when a head hits an object, in a car crash or playing sports.
However, up to 80% of the concussions suffered by military members in Iraq and Afghanistan were from blast pressure waves, usually from an improvised explosive device.
Explosions like that affect the brain differently than concussions caused by mechanical forces.
Dr. Stephen Rao studied nearly 100 military personnel and civilians. They asked their subjects to perform a task which would measure their impulse control. At the same time, their brain activity was being recorded with an MRI scanner.
They found that blast-related concussions caused a different pattern of brain activity than mechanical concussions.
Dr. Rao says that translates into different behavior, notably the inability to control impulses.
That may lead to heavy drinking, gambling, or other risky actions.
He says often, those have been assumed to be part of post-traumatic stress disorder, when it's actually caused by the brain injury.
"There have been a number of animal studies to demonstrat differences between blast versus mechanical injuries. Our study is the first to demonstrate this in humans," said Rao.
Although the subject needs more study, the results could help doctors tailor rehabilitation treatment to the type of concussion.