WASHINGTON -- Almost a quarter million American troops diagnosed with traumatic brain injury are at risk of developing a degenerative disease that causes bursts of anger and depression and can lead to memory loss, difficulty walking and speaking, paranoia and suicide, according to military researchers.
At present, medical officials cannot diagnose or prevent the disease, called Chronic Traumatic Encephalopathy, and there is no known treatment for it, said Army Col. Dallas Hack, director of the Army's Combat Casualty Care Research Program.
But researchers are hot on the trail of new procedures to detect and diagnose the disease, and there is hope that early detection of brain injury among troops exposed to blasts from improvised explosive devices in Afghanistan could prevent them from falling victim to CTE.
"We don't fully understand the incidence of CTE with the occurrence of traumatic brain injury," said Air Force Lt. Col. Randall McCafferty, chief of neurosurgery at the San Antonio Military Medical Center. "But we may be able to learn that early treatment of the initial acute [brain] injury may avoid this cascade from brain injury to CTE."
According to the most recent Pentagon data, 244,217 U.S. military men and women have been diagnosed with TBI, often caused by one or more exposures to bomb blasts. Thousands more are believed to have experienced undiagnosed mild brain damage from blast injuries.
Such invisible wounds, which can be so damaging to veterans and their families long after they return home, are only part of a broad wave of problems and challenges confronting the 2.5 million Americans who have served in Iraq and Afghanistan.
The enduring repercussions of a decade of war range from CTE and other forms of combat trauma to severe physical wounds and difficulties adjusting back into the civilian job market, education and social scene.
The grim effects of CTE have been observed among boxers and other athletes for years. But only recently have researchers been able to demonstrate a link between TBI, an increasingly common form of combat injury, and CTE.
The research demonstrated that even those who have suffered mild TBI -- commonly believed to be a less serious condition -- can develop CTE.
Working with donated brains of patients with CTE, researchers at the Boston Brain Bank -- a collaboration between Boston University and the Department of Veterans Affairs -- have identified a neurological condition that involves an abnormal alteration of a nerve cell called the tau protein.
Dr. Ann McKee, a neuropathologist and co-director of the Center for the Study of Traumatic Encephalopathy in Boston, studied the brains of 21 military veterans, including those who served in Vietnam, the 1991 Gulf War and Iraq and Afghanistan, and all of whom suffered from CTE. Of the four veterans who had served in Iraq or Afghanistan, three also had suffered from post-traumatic stress disorder, which is commonly associated with TBI.
In these cases, McKee was able to find microscopic evidence of the distortion of the tau protein.
"Four years ago we really did not understand this injury at all," McKee said Wednesday in a conference call with reporters. "Now we know it exists. We know it's a problem." Military personnel who are exposed to blast "are at risk" of developing CTE, she said. "But we have no idea of the level of risk. All we can say is we have identified it and it is a problem with some individuals."
In addition to putting combat veterans at risk of developing CTE, researchers suspect that TBI can accelerate the development of Alzheimer's disease, which is marked by progressive mental deterioration.
Research continues at the Boston Brain Bank and elsewhere, focused on identifying markers in the bloodstream or spinal fluid that could signify the presence of CTE. Other research is aimed at developing ways to "tag'' the damaged tau protein so that it shows up in micro-imaging tests.
"Because this is a progressive disease, our main focus is not just on identifying it but learning how to identify it early and treat it so we don't have individuals who suffer these injuries coming down with a devastating disorder later in life," McKee said. Early indications are that simple rest may be one of the best ways to prevent TBI from spiraling into CTE, she said.
At the Army's Combat Casualty Care Research Center, at Fort Detrick, Md., researchers are finalizing a clinical trial involving 2,000 patients, testing procedures that could detect the tau protein in blood minutes after a blast occurred. "Early results show we're on the right track," said Hack, the director of the Army's Combat Casualty Care Research Program. But it will be two years before the trial is completed and the Army can seek regulatory approval to begin using the procedures in the field.
The risk to troops of developing CTE "is a huge issue," Hack said. "It's a bit frustrating to me that it's taken us this long to understand the problem. But now we have -- and we are working it."