Army Spec. David Hunt made it through a year of deployment in central Iraq largely unscathed. But two years after returning to the United States, he faces medical retirement from the military.

As Hunt, 37, describes it, there’s “really not any place” for him in the Army because of chronic migraine, the condition that has plagued him ever since an off-duty auto accident in 2006.

He has fought the symptoms (nausea, vomiting, sensitivity to light) through deployments to the Arizona-Mexico border as well as Iraq. He recalls one particularly bad migraine hitting while he was alone and on guard in Arizona, and he vomited while seeking shelter from the harsh sun. “I did everything I could to just sit up and keep watch,” he said.

Hunt isn’t alone. Over the past decade, migraine and headache have become a significant problem for U.S. armed forces. A 2008 Defense Department report said diagnoses of migraine increased across all branches of the military between 2001 and 2007. Another, more recent study found that, among nearly 1,000 soldiers evacuated from Iraq and Afghanistan because of some form of headache between 2004 and 2009, two-thirds did not return to duty. “Headaches represent a significant cause of unit attrition in personnel deployed in military operations,” the study concluded.

The stress and physical demands of serving in combat areas can trigger head pain, according to experts, and concussions and head traumas increase the likelihood that service members will later develop debilitating headaches and migraines.

Growing recognition has positioned headache and migraine among such issues as post-traumatic stress disorder as a military health concern, and the Defense Department is funding millions of dollars in research. Scientists are evaluating new treatments and therapies that could benefit not only military personnel but also civilians, the estimated 6 percent of men and 18 percent of women who have at least one migraine a year.

A 2009 study of more than 1.2 million U.S. participants in the Iraqi and Afghan military actions found the number who received a diagnosis of migraine increased 40 percent after a tour of duty.

The post-deployment diagnosis was especially common among those who had experienced concussion, anxiety or depression. Ten percent of men and 20 percent of women who had a concussion subsequently got their first migraine diagnosis.

More than 6 percent of men and more than 16 percent of women with a history of anxiety or depression while in the war zone then developed migraine.

Anxiety and depression continue to be issues post-deployment and are frequently linked to migraine symptoms, as is post-traumatic stress disorder. Together, these problems dramatically reduce the quality of life: According to Lt. Col. Jay Erickson, a physician at the Madigan Army Medical Center in Tacoma, Wash., one in three service members with migraine is moderately or severely disabled by the condition post-deployment as determined by the widely used Migraine Disability Assessment test.

As is true in the general population, frequency of migraine can vary widely, said Erickson, who treats many soldiers for neurological problems. “Some have only one migraine every three to six months, whereas others have a migraine on a near daily basis,” he said. “On average, however, we find they have three to five migraines per month.”

That rate is similar to what’s seen among civilians, as is the pain level and duration of the attacks. There is a substantial difference, however, among those troops known to have suffered head trauma. Afflicted soldiers who have had concussions have “much more frequent attacks,” Erickson said.

Ann Scher, a headache researcher at the Uniformed Services University in Bethesda, Md., has been closely following about 400 service members who returned to Colorado’s Fort Carson from Iraq and Afghanistan. Early data show that 30 percent of those who experienced a mild traumatic brain injury (TBI), which includes concussion, experience migraine; adding in probable migraine or migrainelike headache, the rate goes up to 54 percent.

In addition, Scher has found that service members who experienced mild TBI tend to have a continuous, low-grade headache punctuated by episodes of migraine. Some also experience unusually long-lasting aura, a symptom of migraine that includes disturbance of vision.

Treatments for people with post-traumatic headache and migraine are the same as for patients who have not served in war zones: nonsteroidal anti-inflammatory drugs, which restrict blood flow; triptans, a newer class of drugs that act on nerve receptors; and cognitive therapy to prevent or relieve symptoms.

Few truly novel medications and treatments for any kind of headache or migraine have made it to market in the past decade, but the research pipeline has picked up in recent years.

Interest from the military “has helped migraine gain traction,” said David Dodick, a headache researcher at the Mayo Clinic in Scottsdale, Ariz. Since 2007, four Defense Department projects specific to post-traumatic headache and migraine treatment have received $2.4 million in congressional funds.

That adds on to approximately $19 million a year in migraine and headache research funding from the National Institutes of Health, according to Robert Shapiro, a researcher and president of the Alliance for Headache Disorders Advocacy.

“I give the DOD credit for beginning to take initiative,” Shapiro said, adding that the military’s interest is “changing the perception of this valid neurological disorder” and making the need for new treatments a higher priority.

Among the DOD projects is one by Erickson, who is performing a randomized clinical trial to compare three medications and a placebo in service members with chronic post-traumatic headache.

“The three we’re testing are medications that are commonly used to treat (traditional) migraine and headache, and so we think that there’s a good possibility that these will be effective for treating post-concussive headaches,” Erickson said.

In another project, Yu-Qing Cao of Washington University in St. Louis has been researching the role of cytokines, a kind of protein that can promote inflammation. If, as Cao hypothesizes, the cytokines contribute to and/or maintain migraine, anti-cytokine therapies could be used to alleviate the pain, particularly among chronic sufferers. Cao said she is already seeing positive results in mice.

The new federal project with the most funding, more than $1 million, is being run by Andrew Charles, director of the Headache Research and Treatment Program at UCLA, and Peter Goadsby, director of the Headache Center at the University of California at San Francisco. The two are examining the role of neurochemical signals in migraine and will evaluate three commonly used medications, none currently used for migraine, that affect signaling pathways.

The work is in its early stages, Charles said, adding that “it’s difficult” to find funding for research, and “the military is rightly starting to recognize what a substantial problem (headache and migraine) is for service men and women” by making this kind of investment.

Researchers agreed that while the differences between post-traumatic migraine and traditional migraine are not yet fully understood, successful treatments for one might be effective in both. Charles also said that “new treatments could work not just for migraine but other headaches, in lower doses.”

The effectiveness of treatments, however, varies widely. Army Spec. Hunt, for example, had to go through several medications before finding one that worked for him: propranolol, with which he has been almost migraine-free for three months.

Still, he remains frustrated. “They stopped my career,” he said of his migraines. Medication sustained Hunt through his missions in Arizona and Iraq, but the migraines noticeably affected his performance, and he was removed from his unit for medical reasons when he returned to the United States.

Hunt has since spent his time at Fort Lewis in Washington state in a transitional battalion where soldiers get care for their medical conditions and plan their next step. Hunt said he decided to pursue medical retirement because no combat-related specialties will take a soldier with his condition and he would probably have to work in administration or something similar.

Migraine is “headache times 10,” Hunt said. “It’s really hard to handle that while shooting, moving and communicating.”