February 23 (HealthDay News) -- Headaches have become a common complaint among soldiers who suffered mild head trauma while serving in Iraq or Afghanistan.

These headaches tend to be debilitating, mirroring migraines in intensity, according to research released Monday that is to be presented next month at the American Academy of Neurology's annual meeting in Seattle.

About 15 percent of soldiers deployed to Iraq experience mild traumatic brain injury (TBI), according to background information from the researchers, who are based at Madigan Army Medical Center in Tacoma, Wash.

But not much has been known about the headaches that can occur as a result.

Research presented at the AAN meeting last year determined that almost 20 percent of U.S. soldiers returning from Iraq are being diagnosed with migraines. This group also has nearly double the risk for depression, post-traumatic stress disorder and other psychiatric troubles.

For this new study, 978 soldiers returning from Iraq and Afghanistan filled out 13-item questionnaires. Almost all of the participants were male, average age 27, and all had been stateside less than three months at the time of the interview.

All had suffered a concussion or head injury or experienced a blast exposure while overseas, and 97.8 percent reported having headaches.

On average, men (and some women) experienced headaches 8.4 days per month; average duration was 4.4 hours. Thirty percent of these soldiers had headaches 15 or more days each month.

In slightly more than two-thirds of respondents, the headaches started within one week of the injury or blast. Headaches started within one to four weeks in 20 percent of these soldiers.

Among those whose headaches started sooner, 60 percent had headaches with three or more characteristics of a migraine, while 40 percent had headaches they described as interfering with daily life.

Experts noted the new findings should help doctors be on the lookout for these cases.

"Before this particular study came out, little was known about the prevalence, types of headaches, duration of headaches, and risk factors for post-traumatic headaches and U.S. soldiers injured in Iraq and Afghanistan," said Dr. Brian M. Grosberg, director of the Inpatient Headache Program at Montefiore Headache Center in New York City. "Primary-care physicians, neurologists and health-care professionals are going to have to be aware of the implications of service."

"This gives us some clues on types of headaches to be looking out for," added Keith A. Young, vice chair for research at Texas A&M Health Science Center's department of psychiatry and behavioral science neuroimaging and genetics core leader at the VA Center of Excellence for Research on Returning War Veterans at Central Texas Veterans Health Care System. "There may be some tools to help clinicians make a better diagnosis and know that someone needs to be recalled and looked at a year from now."

"Almost 100 percent of these people had headaches at some point, and some 30 percent had them every day or every other day," Young said. "That's really significant."

Grosberg added, "This study highlights the occurrence, the type of headache, the impact of headache and, certainly, with 1.6 million U.S. military personnel having been deployed since the start of military operations in 2001, this is important."

SOURCES: Brian M. Grosberg, M.D., director, Inpatient Headache Program, Montefiore Headache Center, and assistant professor, neurology, Albert Einstein College of Medicine, New York City; Keith A. Young, Ph.D., vice chair, research, Texas A&mpM Health Science Center, department of psychiatry and behavioral science neuroimaging and genetics core leader, VA Center of Excellence for Research on Returning War Veterans at Central Texas Veterans Health Care System; April 25-May 2, 2009, presentation, American Academy of Neurology annual meeting, Seattle