Among troops returning from the Iraq and Afghanistan wars, estimates of traumatic brain injury and the PTSD that often results are staggering.

At least 350,000 are predicted to have PTSD or depression and 370,000 percent are expected to sustain a traumatic brain injury, according to a 2008 study by the RAND Center for Military Health Policy Research called “The Invisible Wounds of War”.

Mental health experts believe that the number of soldiers experiencing any or all of the three conditions will rise to one million by the time the wars are over.

“There’s one million of our citizens that will need some serious rehabilitation,” said Dr. Thomas Horvath, Chief of Staff of the Michael E. Debakey Veterans Affairs Medical Center in Houston.

The consequences of even a mild traumatic brain injury can be severe if left untreated. Anxiety, depression, sleeplessness, memory loss, migraines, seizures, aggression, and trouble with language are just some of the complications that can result from a mild brain injury.

“There’s nothing minimal about it,” said Horvath. “It can be quite debilitating, in a subtle and complicated way.”

Yet the long-term psychological and social consequences of mild traumatic brain injury have yet to be studied comprehensively.

“If I could think of one area that still needs a lot more research,” Horvath said, “with imaging, with very sophisticated neurological testing, with the kind of daily life testing rather than just paper-pencil-IQ.”

“Because you might find that behind a lot of homelessness, there are people with head injuries,” he continued.

The little research that exists on the subject suggests a high rate of mild and severe traumatic brain injury among homeless people. Among a group of 100 homeless men in a New York City shelter, researchers at the Mt. Sinai School of Medicine in New York found that eight out of ten reported a head injury that left them unconscious, prior to becoming homeless.

In addition, a Canadian study by the Center for Inner City Health found that half of the homeless men and women surveyed reported experiencing a traumatic brain injury and one in 10 reported a severe head trauma.

Among 2,000 homeless people questioned in Florida, one in four reported having a traumatic brain injury, according to a 2003 study by the Health Care for the Homeless Clinicians Network.

With one in five returning troops from Iraq and Afghanistan expected to come home with a traumatic brain injury, Horvath worried about the consequences of underestimating the potentially debilitating effects of mild TBI.

“Either were going to produce the largest class of angry, anti-social, actors-out… Or we’re gonna rehabilitate them...and make them as useful citizens as when they were in the service.”

A conversation with Dr. Thomas Horvath, Chief of Staff at the Michael E. Debakey VA Hospital in Houston.