Objective: Use diffusion tensor imaging to investigate white matter alterations associated with blast exposure with or without acute symptoms of traumatic brain injury (TBI).
Participants: Forty-five veterans of the recent military conflicts included 23 exposed to primary blast without TBI symptoms, 6 having primary blast with mild TBI, and 16 unexposed to blast.
Design: Cross-sectional case-control study.
Main Measures: Neuropsychological testing and diffusion tensor imaging metrics that quantified the number of voxel clusters with altered fractional anisotropy (FA) radial diffusivity, and axial diffusivity, regardless of their spatial location.
Results: Significantly lower FA and higher radial diffusivity were observed in veterans exposed to primary blast with and without mild TBI relative to blast-unexposed veterans. Voxel clusters of lower FA were spatially dispersed and heterogeneous across affected individuals.
Conclusion: These results suggest that lack of clear TBI symptoms following primary blast exposure may not accurately reflect the extent of brain injury. If confirmed, our findings would argue for supplementing the established approach of making diagnoses based purely on clinical history and observable acute symptoms with novel neuroimaging-based diagnostic criteria that “look below the surface” for pathology.
Mid-Atlantic Mental Illness Research Education and Clinical Center, Durham, North Carolina (Drs Taber, Hurley, Rowland, Lamar, and Morey and Ms Haswell); Research and Education Service Line, W. G. (Bill) Hefner VA Medical Center, Salisbury, North Carolina (Drs Taber, Hurley, Rowland, Hurt, and Lamar); Division of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Blacksburg, Virginia (Dr Taber); Departments of Physical Medicine and Rehabilitation (Dr Taber) and Psychiatry and Behavioral Sciences (Dr Hurley), Baylor College of Medicine, Houston, Texas; Departments of Psychiatry and Behavioral Medicine (Drs Hurley and Rowland), Radiology (Dr Hurley), Neurobiology and Anatomy (Dr Rowland), Wake Forest School of Medicine, Winston-Salem, North Carolina; Durham VA Medical Center, Durham, North Carolina (Ms Haswell and Dr Morey); Duke-UNC Brain Imaging and Analysis Center (Ms Haswell and Dr Morey) and Department of Psychiatry and Behavioral Sciences (Dr Morey), Duke University, Durham, North Carolina.
Corresponding Author: Katherine H. Taber, PhD, Research Health Scientist, W. G. (Bill) Hefner VA Medical Center, Research and Education Service Line, Mailstop 11M, 1601 Brenner Ave, Salisbury, NC 28144 (Katherine.firstname.lastname@example.org).
This research was supported by a grant from the Department of Defense, Joint Improvised Explosive Device Defeat Organization (51467EGJDO), the Department of Veterans Health Affairs Rehabilitation Research and Development (RX000389-01), and with resources of the Mid-Atlantic Mental Illness Research, Education, and Clinical Center and W. G. (Bill) Hefner VA Medical Center.
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, the Department of Defense, or the US government.
The authors declare no conflicts of interest.