The slightest brain injury — even one barely detectable by an ultra-sensitive imaging test — could put a soldier at greater risk for post-traumatic stress disorder (PTSD), according to a University of Rochester Medical Center (UMRC) study.
The findings are important for doctors who care for troops after deployment, as they try to decipher and treat the overlapping symptoms of PTSD and mild traumatic brain injury (mild TBI).
Previously, the complex interplay between TBI and PTSD was unclear. Researchers believe they are the first to discover a link that can be proven with advanced imaging techniques.
“Most people believe that, to a large extent, chronic stress from intense combat experiences triggers PTSD. 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,” said lead author Jeffrey J. Bazarian, M.D., M.P.H., associate professor of emergency medicine at URMC, and a member of the 2007 Institute of Medicine committee that investigated brain injuries among war veterans.
It has been estimated that 320,000 troops suffered concussions in Iraq and Afghanistan by 2008.
Bazarian’s research included 52 war veterans from western New York who served in combat areas between 2001 and 2008. Approximately four years after their final tour of duty, veterans were asked about PTSD symptoms, blast exposures, mild concussions, and combat experiences.
Study participants were given the standard Walter Reed Institute of Research Combat Experiences Survey to measure combat stress. The survey asks about the intensity of deployment duties (such as handling or uncovering remains), exposure to explosive devices, vehicle accidents, falls or assaults, and events such as being ambushed or knowing someone who was seriously injured or killed.
The veterans were also given standard MRI tests, as well as a more sensitive test called diffusion tensor imaging, or DTI, which has been used to detect axonal injury, a type of neuronal damage that occurs during a concussion.
Of the 52 veterans, 30 suffered at least one mild traumatic brain injury, and seven reported having more than one. Sixty percent of the veterans were exposed to one or more explosive blasts.
Every single veteran had one or more PTSD symptoms, and 15 met the formal criteria for PTSD, which is a devastating psychiatric illness. The severity of veterans’ PTSD symptoms correlated with the amount of axonal injury seen on the DTI scans.
Furthermore, five of the 52 veterans showed abnormalities on standard MRI scans, and their PTSD severity was much worse than the 46 veterans with normal MRIs.
Interestingly, PTSD severity did not correlate with the clinical diagnosis of mild TBI. This suggests that mild brain injury can be present without triggering the loss of consciousness or amnesia that is commonly associated with diagnosis of mild TBI, and that this injury may make a person more susceptible to mental illness when coupled with extreme chronic stress.
“Based on our results, it looks like the only way to detect this injury is with DTI/MRI,” Bazarian said.
“While it may not be feasible due to costs and limited availability of some neuroimaging tests to screen thousands of service members for brain injury, our study highlights the pressing need to develop simpler tests that are accurate and practical, that correlate with brain injury.”
The study is published online by the Journal of Head Trauma Rehabilitation.