Under a microscope, brain sections from three different individuals show axons with large, bulb-shaped lesions characteristic of a motor vehicle crash (left); many smaller lesions characteristic of a blast injury (center); and fewer lesions characteristic of an opiate overdose (right). (Courtesy of Vassilis Koliatsos)

Scientists have discovered what a traumatic brain injury, or TBI, suffered by a quarter-million combat veterans of Iraq and Afghanistan looks like, and it’s unlike anything they’ve seen before: a honeycomb pattern of broken connections, primarily in the frontal lobes, our emotional control center and the seat of our personality.

“In some ways it’s a 100-year-old problem,” said Vassilis Koliatsos, a Johns Hopkins pathologist and neuropsychiatrist. He was referring to the shell-shock victims of World War I, tens of thousands of soldiers who returned home physically sound but mentally wounded, haunted by their experiences and unable to fully resume their lives.

“When we started shelling each other on the Western Front of World War I, it created a lot of sick people . . . . [In a way,] we’ve gone back to the Western Front and created veterans who come back and do poorly, and we’re back to the Battle of the Somme,” he said. “They have mood changes, commit suicide, substance abuse, just like in World War I, and they really do poorly and can’t function. It’s a huge problem.”

Many of the lingering symptoms of shell shock, or what today is known as neurotrauma, are the same as they were a century ago. Only the nature of the blast has changed, from artillery to improvised explosive devices.

Koliatsos and colleagues, who published their findings in the journal Acta Neuropathologica Communications in November, examined the brains of five recent U.S. combat veterans, all of whom suffered a traumatic brain injury from an IED but died of unrelated causes back home. Their controls included the brains of people with a history of auto accidents and of those with no history of auto accidents or TBI. Koliatsos says he was prompted to do this study because he is both a pathologist and a neuropsychiatrist, and he sees many TBI cases, both in veterans and in young people with sports concussions.

“Their attention is off, mood is off, personality is off. They’re impulsive, aggressive, do poorly in school. . . . I wanted to help my patients by trying to understand what is going on in their brains.”

What he found surprised him. The “neural signature” for blast victims was distinctly different from those who suffer TBIs in car accidents.

“We saw a type of disease in the brain not seen before,” he said. “We didn’t even know if we’d see any sign of disease.”

The scientists searched for amyloid precursor protein, which is transmitted between neurons along a fiber known as an axon. TBIs cause those axons to break, and the protein coalesces at those breaks, causing swelling. In car accidents, those swellings are large and bulbous, but in the veterans’ brains they were smaller and formed a honeycomb pattern near blood vessels.

The researchers also noticed that these unusual swellings were particularly evident in the frontal lobes, the seat of executive functions.

Once World War I ended, blast injuries were not the leading cause of combat injury until the American-led invasion of Iraq in 2003. The Vietnam War, however, did produce the first diagnosed cases of post-traumatic stress disorder, which Koliatsos believes has helped to stigmatize IED survivors who return home but have enormous difficulties adjusting.

“We thought it was hysteria in World War I and then came PTSD in Vietnam,” he said, so we continued to think of these [hidden] injuries only as psychological.”

So did the poet Wilfred Owen, one of Great Britain’s most famous shell-shock victims, who spent a year in a psychiatric hospital before returning to the front, where he was killed in action a week before the armistice of 1918.

Of himself and his fellow shell-shock patients, Owen wrote: “These are men whose minds the Dead have ravished.”