All it takes is a single explosion…

Blunt head trauma and traumatic brain injuries are well-known artifacts of war. The Brain Trauma Foundation reports that between 10-20% of Iraq veterans (approximately 150,000-300,000 individuals) suffer from some level of TBI.  That’s a lot of former soldiers who may be experiencing symptoms like impulsive behavior, loss of memory, personality changes, cognitive fatigue and epilepsy.

Of course, TBI is not exclusive.  They are far more common in the civilian world.  Car accidents, contact sports, assaults and falls can also result in TBI or chronic traumatic encephalopathy (CTE), a condition that shares many clinical features with TBI. 

While many neuroscientists are diligently studying the biological mechanisms of both TBI and CTE, trying to understand how a blow to the head can result in such widespread brain injury (with so many debilitating behavioral effects), there’s been a pervasive idea that either extremely severe or multiple blasts are required to set off the “cytotoxic cascade” of brain events involved in serious damage.  New research from researchers at Boston University, the New York Medical College (NYMC) and the Veterans Affairs Boston Healthcare System, however, suggests that even a single blast can lead to long-term impairment.  The study was published this week in Science Translational Medicine. 

The researchers performed neuropathological analyses on four military personnel who had been exposed to blasts or concussive injury during their tours, three young athletes with history of multiple concussions and four comparably aged controls.  These analyses, of course, were done post-mortem.  It’s probably no surprise that the soldiers and athletes had brains that looked eerily similar, with similar CTE-like neurodegenerative injury observed. Multiple blows to the head, whether received in a football game or from multiple IED blasts, can do some serious cumulative damage.

But the group took the work a step further. They collaborated with some blast physics experts and created a neurotrauma blast mouse model to examine the effects of single blast across the brain.  They found that only two weeks after a single explosive blast, the mice showed significant CTE damage, as demonstrated by neurodegeneration and persistent learning and memory deficits.  These symptoms lasted for a month. 

I know quite a few soldiers who could have told you that a single blast is all it can take to shake up your noggin but good.  This work appears to substantiate the story of your basic grunt.  But what about preventing TBIs?  If blasts or hits to the head are just part and parcel of your job, can anything be done to stop that cytotoxic cascade before the damage is done?

The answer may be yes.  When the researchers immobilized the head of the mice during the blast in this study, they found that the animals did not show the same learning and memory problems afterwards.  It’s possible that creating a military or sports helmet that can immobilize the head can limit damage in the future.  It’s certainly worth a shot–because, let’s face it, the IEDs probably aren’t going anywhere.

Scientists are only beginning to understand the molecular and cellular mechanisms that result TBI and CTE damage.  They are studying these effects with the hope that by understanding these processes, they can find targets for treatments after the injuries are sustained.  But it’s nice to see that researchers are also considering prevention.  Given that we’ll be in Afghanistan for some time to come, that may be even more important.

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