WASHINGTON, Jan. 2011 – Service members who suffer mild traumatic brain injuries in combat and then struggle with depression, irritability, alcohol abuse and similar problems after they return home most likely are experiencing post-traumatic stress, rather than brain injury symptoms, according to a new study.

The study, sponsored by the Defense and Veterans Affairs departments and published in this month’s Archives of General Psychiatry, a Journal of the American Medical Association publication, tracked Minnesota National Guard soldiers during the last month of their 16-month deployment to Iraq, then again a year after they returned home.

The findings, based on the self-reporting of 953 soldiers with follow-ups from the clinicians, showed “very little evidence for a long-term negative impact” from concussions or mild TBI on “psycho-social outcomes” –- anxiety, depression, drug and alcohol abuse and the like -- after accounting for post-traumatic stress, said Melissa A. Polusny, a clinical psychologist at the Minneapolis Veterans Affairs Health Care System and a professor at University of Minnesota Medical School.

Polusny wrote the study along with five other clinical psychologists, and in collaboration with Army Col. (Dr.) Michael Rath, a surgeon with the 34th Infantry Division brigade that participated in the study.

“After we statistically controlled for PTSD symptoms, there were virtually no long-term symptoms from concussive and mild TBI,” she said.

Polusny emphasized that the study only investigated mild TBI, which may cause a person to be momentarily dazed or confused or lose consciousness for fewer than 20 minutes, but causes no actual injury to the brain or skull. Also, the study did not consider repeated head trauma -– the subject of other studies that have suggested long-term effects -– in the soldiers, 95 percent of whom were on their first deployment to Iraq in 2005, she said.

The study’s focus on mild TBI is significant for today’s warfighters, Polusny said, because “the vast majority of reports of TBI are mild.”

The study’s findings, she added, are “very interesting and not exactly what we expected.”

The findings show that service members are much more likely to report concussions and mild traumatic brain injuries after they return home than they are in the combat theater. Of those surveyed, only 9 percent reported concussions or TBI in theater, but 22 percent reported incidents after redeployment.

Similarly, 9 percent reported symptoms of post-traumatic stress disorder in theater, compared to 14 percent at home; and 9 percent reported symptoms of depression, compared to 18 percent at home.

Many of the soldiers who answered that they did not have mild TBI or post-traumatic stress disorder symptoms actually did, the VA’s publication brief of the study says. Of those, 64 percent reported having problems with distractibility and irritability, 60 percent reported memory problems, 57 percent reported ringing in the ears, and 23 percent had balance problems.

Another notable finding, Polusny said, is that after their return home, more than 40 percent of the Iraq war veterans reported some levels of alcohol abuse.

“There’s been a lot of attention paid to PTSD and mild TBI and even suicide risk, but the prevalence of problem drinking appears to be much higher among returning service members than any of these other problems,” she said.

Researchers were surprised at the wide difference in reporting from the war theater to home, Polusny said. They believe the disparity may be due to service members’ reluctance to report problems while deployed, or that they have a different impression of events when they return home, she said. The differences may reflect a need for better post-deployment questioning of veterans, she added.

“One of the really important implications of the findings is that we need to be carefully screening for PTSD, and make sure veterans receive treatment,” Polusny said.

Polusny added that the findings caused concern that combat veterans may misattribute the reason for their problems, which could hamper treatment or cause a service member to not seek treatment.

“If a veteran is having irritability and memory problems, and assumes he had a concussion when maybe he is suffering from PTSD symptoms, … we need to make sure we are treating veterans for the right problems,” she said.

The study did not investigate the cause of the PTSD or whether the TBI triggered it.

“The events that surround a concussion or mild TBI in theater -- being exposed to a blast or being in a firefight -- those kinds of events already place someone at risk of PTSD,” Polusny said. “Is that due to injury to the brain, or the situation they are in? We can’t piece that apart yet.”