Lead author Dr. Jeffrey J. Bazarian of the University of Rochester Medical Center said the nature of the interaction between traumatic brain injury and PTSD had been unclear until now.
"Most people believe that, to a large extent, chronic stress from intense combat experiences triggers PTSD," Bazarian said in a statement. "Our study adds more information by suggesting that a physical force such as exposure to a bomb blast also may play a role in the genesis the syndrome."
Bazarian's research involved 52 war veterans from western New York who served in combat areas from 2001 to 2008. Approximately four years after their final tour of duty, Bazarian and colleagues asked each veteran about PTSD symptoms, blast exposures, mild concussions and combat experiences.
The study, published online by the Journal of Head Trauma Rehabilitation, found 30 of the veterans suffered at least one mild traumatic brain injury, and seven reported having more than one. Sixty percent were exposed to one or more explosive blasts.
All 52 veterans had one or more PTSD symptoms, and 15 met the formal criteria for PTSD -- a devastating psychiatric illness. The severity of veterans' PTSD symptoms correlated with the amount of axonal injury seen on the brain scans, the study said.