Objective: To understand the relations of mild traumatic brain injury (TBI), blast exposure, and brain white matter structure to severity of posttraumatic stress disorder (PTSD).
Design: Nested cohort study using multivariate analyses.
Participants: Fifty-two OEF/OIF veterans who served in combat areas between 2001 and 2008 were studied approximately 4 years after the last tour of duty.
Main Measures: PTSD Checklist-Military; Combat Experiences Survey, interview questions concerning blast exposure and TBI symptoms; anatomical magnetic resonance imaging (MRI), and diffusion tensor imaging (DTI) scanning of the brain.
Results: PTSD severity was associated with higher 1st percentile values of mean diffusivity on DTI (regression coefficient [r] = 4.2, P = .039), abnormal MRI (r = 13.3, P = .046), and the severity of exposure to combat events (r = 5.4, P = .007). Mild TBI was not significantly associated with PTSD severity. Blast exposure was associated with lower 1st percentile values of fractional anisotropy on DTI (odds ratio [OR] = 0.38 per SD; 95% confidence interval [CI], 0.15–0.92), normal MRI (OR = 0.00, 95% likelihood ratio test CI, 0.00–0.09), and the severity of exposure to traumatic events (OR = 3.64 per SD; 95% CI, 1.40–9.43).
Conclusions: PTSD severity is related to both the severity of combat stress and underlying structural brain changes on MRI and DTI but not to a clinical diagnosis of mild TBI. The observed relation between blast exposure and abnormal DTI suggests that subclinical TBI may play a role in the genesis of PTSD in a combat environment.
Departments of Emergency Medicine (Dr Bazarian), Biostatistics and Computational Biology (Dr Peterson), and Imaging Sciences (Dr Zhong), University of Rochester School of Medicine, Rochester; VA Western New York Healthcare System – Buffalo, Buffalo (Dr Donnelly); and Canandaigua VAMC, Canandaigua (Dr Warner), New York.
Corresponding Author: Jeffrey J. Bazarian, MD, MPH, Department of Emergency Medicine, University of Rochester School of Medicine, 601 Elmwood Ave, Rochester, NY 14642 (firstname.lastname@example.org).
This research was supported by a grant from the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, and Health Services Research and Development (SDR 06-162). The authors thank Leslie Charles (Canandaigua VA), Samuel Z. Lewis (Canandaigua VA), and Michelle Alt (VA Western New York Healthcare System – Buffalo) for their assistance in subject recruitment and data collection and to P.-L. Westesson, MD, PhD, DDS, for magnetic resonance imaging interpretation.
The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the US government.
The authors declare no conflicts of interest.