TUESDAY, April 19 (HealthDay News) -- Nearly one-third of people who suffer a traumatic brain injury (TBI) will experience depression after the injury, a new study finds.

A team at Vanderbilt University Medical Center analyzed existing research on blunt force trauma head injuries suffered by civilians in traffic accidents, falls, sports and assaults.

"Any patient who has a traumatic brain injury is at a real risk for developing depression, short and long term," study co-author Dr. Oscar Guillamondegui, an assistant professor in the trauma and surgical critical care division, said in a medical center news release.

"It doesn't matter where on the timeline that you check the patient population -- six months, 12 months, two years, five years -- the prevalence is always around 30 percent across the board."

The rate of depression in the general population is about 9 to 10 percent, Guillamondegui said.

Each year, U.S. hospital emergency departments treat 1.2 million cases of traumatic brain injury. These findings suggest that about 360,000 of those patients will suffer depression after their head injury.

The study authors said their findings about the high rate of post-injury depression are especially important considering the lack of research on whether antidepressants are a safe and effective treatment for brain-injured people.

"Even though it is possible that individuals with TBI and depression may warrant different approaches to treatment than the general population with depression, there were only two studies of treatment in this population," co-author Melissa McPheeters, co-director of the Vanderbilt Evidence-based Practice Center, said in the news release.

"It's unacceptable, with so many people sustaining TBIs -- both in combat and civilian life -- that we know so little about treating depression in this population," she added.

More information

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