PTSD confounds detection of compromised cerebral white matter integrity in military veterans reporting a history of mild traumatic brain injury

Abstract

Primary objective: Based on high comorbidity between mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) among deployed military service members, this study tested the hypothesis that the presence of PTSD disrupts the association between mTBI and lower white matter integrity identified in non-military samples.

Research design/Methods and procedures: In a sample of 124 recent veterans with a range of mTBI and PTSD history, diffusion tensor imaging (DTI) metrics of white matter integrity in 20 regions were compared using multiple mTBI and PTSD contrasts.

Main outcomes and results: Civilian mTBI was associated with lower global anisotropy, higher global diffusivity and higher diffusivity in 17 of 20 regions. No main effects of deployment mTBI were observed, but an interaction between deployment mTBI and lifetime PTSD on FA was observed globally and in 10 regions. Impact and blast mTBI demonstrated similar but weaker effects to those of civilian and deployment mTBI, respectively, demonstrating the context of mTBI is more relevant to white matter integrity than mechanism of injury.

Conclusions: Overall, a main effect of civilian mTBI indicates long-term disruptions to white matter are likely present, while the interaction between deployment mTBI and PTSD indicates that a history of PTSD alters this relationship.

Keywords:

• PTSD
• mTBI
• white matter
• concussion
• military
• DTI

Acknowledgements

The authors would like to thank Bridget Doane, Carolyn Anderson and Craig Marquardt for assistance with consensus review of mTBI and clinical diagnoses. We would also like to thank the Veterans who participated for their time and willingness to contribute to Veteran research. The views expressed in this article are those of the authors and do not necessarily represent the views of the Department of Veterans Affairs.

Declaration of interest

This research was supported by a VA Rehabilitation R&D Merit Review Award (I01RX000622) to Dr. Sponheim, a VA Rehabilitation R&D Career Development Award (IK2RX000709) to Dr. Davenport and a Chronic Effects of Neurotrauma Consortium Award to Dr. Davenport funded by VA Rehabilitation R&D (I01RX002171) and the Department of Defense (W81XWH-13-2-0095).