A profoundly disturbing report came out a couple of months ago, one that has ominous implications for hundreds of thousands of vets.

Basically, it says that everyone who suffered a brain injury — even a mild concussion – could be at risk of developing degenerative brain diseases later in life that can lead to memory loss, bad judgment, depression, outbursts of anger, thoughts of suicide and potential dementia.

That’s a huge concern because traumatic brain injuries are one of the signature wounds of our wars in Iraq and Afghanistan. According to the most recent Pentagon data, military doctors have confirmed traumatic brain injury in more than 244,000 of the 2.5 million troops who fought in those wars.   And the VA says that more than half the Iraqi/Afghan vets are seeking medical help after returning from service, and that half of them (28 percent of the returning 1.3 million vets) are seeking mental health treatment for PTSD, TBI or major depression.

This new study, “Chronic Traumatic Encephalopathy in Blast-exposed Military Veterans and a Blast Neurotrauma Mouse Model,” was released last May by a national consortium led by Boston University School of Medicine and the Department of Veteran Affairs.   It’s a very small study, comparing the brains of four dead soldiers, four athletes (three football players and a wrestler), and four others who had no history of brain injuries. But it’s a very significant study because, as one of the co-authors told me, it’s not easy for the family of a fallen warrior to donate his brain for research.

For years, doctors have believed that the brain heals itself after injuries. But this study casts doubt on that. It found evidence that even relatively mild brain injuries can worsen over time and end up as chronic traumatic encephalopathy (CTE), a degenerative brain disorder for which there is no treatment.

In all four of the vets and all four of the athletes, doctors found evidence of the beginnings of CTE: dead or dying brain cells, damaged axon fibers that communicate between nerve cells, and abnormal clumps of a toxic protein called protein tau. Protein tau is a normal part of the structure of nerve cells and provides what can be thought of as a railroad track providing nutrients to nerve cells; abnormal clumps of protein tau weaken the structure of nerve cells and reduce their flow of nutrients, according to Dr. Ann McKee, one of the study’s co-authors.

Those symptoms were not present in the third group with no reported concussions.

That merely confirms the conclusions already formed by McKee, co-director of the Center for the Study of Traumatic Encephalopathy at Boston University. A doctor who also directs the neuropathology center for the New England VA Medical Center, McKee has studied the brains of 68 people diagnosed postmortem with chronic traumatic encephalopathy, including 21 military vets, three of whom had previously been diagnosed with PTSD.

“We can show an association, but we don’t understand why a brain injury can trigger progressive neurological degeneration,” McKee told me.

But the team took one additional (and critical) step by developing a blast tube that created a force equivalent to a 120-millimeter mortar round which they aimed at mice.  The study’s other co-author, Lee Goldstein, an Alzheimer’s researcher at the Boston University School of Medicine, told me that it’s important to note that the blast tube didn’t replicate the variable blast conditions in the field – rather it replicated the same brain injury in the mice that doctors had found in human victims. “A single blast imitates a military blast and replicates virtually all aspects of CTE neuropathology found in humans,” Goldstein said.

First a supersonic blast force (a sudden and abrupt release of energy within a localized area) passed through the mice brains, doing relatively little damage. Almost simultaneously, a blast wind of more than 330 mph shook the mice heads, creating what’s called a “bobble-head” effect.

“Even though a shock wave rolled through the mice heads at supersonic speeds, there was no bleeding, no contusions, no rips in the tissue,” said Goldstein. “They looked for all the world like what we see in human cases of traumatic brain injury – the invisible injury that people have been talking about since World War I.”

Two weeks later after blasting the mice, Goldstein and his team found they were experiencing losses of short-term memory and learning capability. Later, when the mice brains were examined under microscopes, scientists found the early signs of CTE, including specialized cells called astrocytes strangling blood vessels, axons crumbling, and long tangles of the tau protein that doctors had previously observed in human Alzheimer’s patients. Goldstein told me that the blast wind damaged two of the longer structures in the mouse brains: small blood vessels and small nerve cells, leading to neural inflammation.

The new study did say that long-term behavioral deficits in mice could be prevented by immobilizing the head, a finding that could be useful to military commanders.

“Our results provide compelling evidence linking blast exposure to long-lasting brain damage,” the study concluded. “Specially, our study raises concerns that blast exposure may increase risk for later development of CTE and associated neurobehavioral sequelae.”

Again, the risk is unclear. “The incidence and prevalence of this disorder are completely unknown,” McKee told me.

But it’s not only combat vets who are at risk. It’s also kids playing combat sports like boxing and football. “The effects of blast exposure, concussive injury, and mixed trauma (blast exposure and concussive injury) were indistinguishable,” said the report.

Finally, it potentially affects all the rest of us who have ever suffered brain injuries. Personally, a quarter of a century ago, I slammed on the brakes and went over the handlebars of a bike.  I landed on my head without a helmet (never again!) and was unconscious from about suppertime until I woke up in an emergency room about dawn the next morning. This report says an injury less severe would put me at risk.

Mitt Romney may also have cause for concern. The Republican presidential nominee, famous for his explosive temper and his verbal gaffes such as introducing vice-presidential nominee Paul Ryan as “the next president of the United States,” was knocked unconscious in 1968 in an auto wreck in France that was so severe that he was mistakenly declared dead at the scene.

It’s unclear how many people afflicted with this kind of head injury will develop a degenerative brain disorder. “We have no idea of the level of risk,” said McKee. “All we can say is that we have identified it, and it is a problem with some individuals.”

Goldstein, however, said the study marked an important step in understanding this injury. “Now we have a mechanism and a model,” he explained, “so we’re well on the road to developing methods of prevention, treatment and rehabilitation.”