Previous research has identified CTE in football players, boxers, wrestlers and other athletes, but this research focuses on the first case series of post-mortem brains from U.S. military personnel who were either exposed to a blast, had a concussive injury or were exposed to a blast that led to a concussive injury.

A scout with 2nd Platoon, Troop A, 1st Squadron, 13th Cavalry Regiment, stands watch over a village during a mission in Laghman province last month. The scouts operate out of Forward Operating Base Mehtar Lam as a counter improvised explosive device platoon. Trained in the art of reconnaissance, the scouts keep a watchful eye on the roads they travel, watching for IEDs before they can detonate and cause harm. Photo from the 7th Mobile Public Affairs Detachment.

Early on, CTE can be identified by the presence of abnormal deposits of the protein tau in the form of neurofibrillary tangles, glial tangles and neuropil threads throughout the brain. Like TBI, CTE can result in long-term psychiatric symptoms, memory problems and learning deficits. In later stages, it can be confused with Alzheimer’s disease.

For the study, researchers compared brain tissue from four military servicemembers having known blast exposure and/or concussive injury with brain tissue samples from three young amateur American football players and a professional wrestler, all of whom had a history of repetitive concussive injury. The servicemembers’ brain samples also were compared to similarly-aged normal controls who never had blast exposure, concussive injury or neurological disease.

CTE neuropathology in the military veterans’ brains was in line with that found in the young athletes and with what previously has been observed in brain samples from other athletes with a history of repetitive concussive injury.

"Our results showed that the neuropathology from blast exposure, concussive injury or both were virtually indistinguishable from those with a history of repeat concussive injury," McKee said in a statement.

McKee, who is the director of the Brain Banks for BU's Alzheimer's Disease Center and the Center for the Study of Traumatic Encephalopathy at the Bedford VAMC, also said the findings suggest that TBI from different causes could result in similar disease pathways in the brain.

Effects of Single Blast

One of the most important findings of the research was the devastating effects of exposure to a single blast and how quickly long-term impairments appeared in the brain.

Collaborating on that aspect of the research were: White River Junction, VT, VAMC; New York Medical College; Fraunhofer Center for Manufacturing Innovation, Brookline, MA; University of Massachusetts Lowell; Lawrence Livermore National Laboratory, Livermore, CA; Massachusetts General Hospital, Boston.

The team's experimental data showed that one blast comparable to that experienced in combat conditions led to both neuropathological and behavioral evidence of CTE, which were observed only two weeks after exposure to the single blast.

With an IED blast wind reaching velocity of 330 mph, “the force of the blast wind causes the head to move so forcefully that it can result in damage to the brain," Goldstein pointed out.

The study not only suggested new diagnostic techniques for diagnosing blast-related brain trauma but also offered techniques to prevent it, including immobilizing the head during a blast exposure.

"Our study provides compelling evidence that blast TBI and CTE are structural brain disorders that can emerge as a result of brain injury on the battlefield or playing field," Goldstein said. "Now that we have identified the mechanism responsible for CTE, we can work on developing ways to prevent it, so that we can protect athletes and our military service personnel."

Authors of a study published last year reported a 27-year-old Marine who committed suicide as a sentinel case of CTE in Iraqi war veterans diagnosed with PTSD. That study said the case could “stimulate new lines of thought and research in the possible pathoetiology and pathogenesis of PTSD in military veterans as part of the CTE spectrum of diseases, and as chronic sequelae and outcomes of repetitive traumatic brain injuries.”2

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1. Goldstein LE, Fisher AM, Tagge CA, Zhang XL, et al. Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model. Sci Transl Med. 2012 May

1. 2. Omalu B, Hammers JL, Bailes J, Hamilton RL, Kamboh MI, Webster G, Fitzsimmons RP. Chronic traumatic encephalopathy in an Iraqi war veteran with posttraumatic stress disorder who committed suicide. Neurosurg Focus. 2011 Nov 31(5):E3. PubMed PMID: 22044102.