- December 11, 2013
Science Daily/University of California, San Diego Health Sciences
In a novel study of U.S. Marines investigating the association between traumatic brain injury (TBI) and the risk of post-traumatic stress disorder (PTSD) over time, a team of scientists report that TBIs suffered during active-duty deployment to Iraq and Afghanistan were the greatest predictor for subsequent PTSD, but found pre-deployment PTSD symptoms and high combat intensity were also significant factors.
Traumatic brain injuries are common. At least 1.7 million Americans annually sustain a TBI, with an estimated 5 million Americans living with TBI-related disabilities. More than half (56.8 percent) of the servicemen reported a TBI prior to deployment; almost a fifth (19.8 percent) reported a TBI during deployment. The vast majority of deployment-related TBIs (87.2 percent) were deemed mild, with less than 24 hours of post-traumatic amnesia. Of the 117 Marines whose TBI resulted in lost consciousness, 111 said it was less than 30 minutes.
"The severity of post-deployment PTSD symptoms depends, in part, on the severity of pre-existing symptoms from prior trauma and combat intensity," said Baker. "An individual with no pre-existing PTSD symptoms and low combat intensity is at minimal risk for developing PTSD -- less than a 1 percent probability. Increases in pre-existing symptom scores and combat intensity modestly increase post-deployment symptom scores by 1 to 2 percent.
"By contrast, deployment-related mild TBI increases post-deployment symptom scores by 23 percent, and moderate to severe injuries increase scores by 71 percent. This percent increase is equivalent to a 14-point increase in combat intensity scores for mild TBI, and a 37-point increase for moderate or severe TBI."
Baker noted many factors, both environmental and individual, may contribute to development of PTSD. Two of the most important are pre-existing psychiatric symptoms and the nature of the "trauma event." "However, TBI was the strongest predictor of PTSD, even when controlling for pre-existing symptoms and combat intensity," she said. "These findings may be used to identify individuals who may be at risk for developing PTSD and provide them with more immediate health care."