That news comes from an Army study of 2,525 soldiers from two combat brigades who completed a yearlong deployment in Iraq.
Suffering a concussion in Iraq was "strongly associated" with posttraumatic stress disorder (PTSD) and physical health problems three to four months after returning home, the study says. Also, PTSD and depression may have played a role in the soldiers' physical health problems.
The study appears in tomorrow's edition of The New England Journal of Medicine.
Three to four months after returning home from Iraq, the soldiers completed an anonymous survey about their combat experiences, injuries, symptoms of posttraumatic stress disorder (PTSD), depression, and physical health problems.
Almost 15% of the soldiers had suffered a concussion in Iraq, including 5% who lost consciousness and 10% who were dazed and confused or saw stars. An additional 17% reported other injuries that didn't involve concussions.
Nearly 44% of soldiers who lost consciousness were diagnosed with PTSD, compared with 27% of those who had concussions but remained conscious, 16% of soldiers with other injuries, and 9% of uninjured soldiers. Depression also often accompanied loss-of-consciousness concussions.
Soldiers who had suffered concussions also reported worse health and missed more days of work.
Hoge's team considered combat factors, including the intensity of the situation in which the concussions occurred. The psychiatric results held.
But after accounting for PTSD and depression, concussions were no longer associated with physical health problems.
PTSD and depression may be "important mediators of the relationship between mild traumatic brain injury [concussion] and physical health problems," Hoge's team writes.
Based on the findings, an editorial published with the study makes two key points:
"First, soldiers who have mild traumatic brain injury [concussion] are at greater risk for health-related problems," writes editorialist Richard Bryant, PhD. "Second, soldiers should not be led to believe that they have a brain injury that will result in permanent change," since stress-related conditions can be managed.
Bryant works for the school of psychology at the University of New South Wales in Sydney, Australia.