Researchers say even seemingly mild head injury should be taken seriously.

(HealthDay) -- People who've had a mild traumatic brain injury have more severe headaches and a greater number of headaches than those who've had moderate to severe brain injury, a new study finds.

"We have known that headache is the most common physical symptom after , but we wanted to study headache prospectively including whether severity of injury had an impact in prevalence," study lead author Dr. Sylvia Lucas, of the University of Washington Medical Center, in Seattle, said in an American Headache Society news release.

She and her colleagues evaluated patients with mild, moderate or severe traumatic brain injury at three, six and 12 months after their brain injury. Those with mild injury were more likely to report new or worse headaches than those with moderate to severe injury.

The study was to be presented this week at an American Headache Society meeting in Los Angeles.

"These findings should caution us to not underestimate seemingly milder head injuries and to take all very seriously," Lucas said.

She noted that recent U.S. Centers for Disease Control and Prevention data show a major increase in the number of emergency department admissions for teens who've suffered sports-related concussions.

Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information: The U.S. National Institute of Neurological Disorders and Stroke has more about traumatic brain injury.