Examining Microstructural White Matter in Active Duty Soldiers with a History of Mild Traumatic Brain Injury and Traumatic Stress
Michael N. Dretsch1, *, Rael T. Lange2, Jeffery S. Katz3, 4, 5, Adam Goodman3, Thomas A. Daniel3, Gopikrishna Deshpande3, 4, 5, Thomas S. Denney3, 4, 5, Grant L. Iverson6, Jennifer L. Robinson3, 4, 5
1 US Army Aeromedical Research Laboratory, Fort Rucker, AL; Human Dimension Division, Headquarters Training and Doctrine Command, 950 Jefferson Ave, Fort Eustis, VA, 23612, USA
2 National Intrepid Center of Excellence, Defense and Veterans Brain Injury Center, Walter Reed National Military Medical Center, Palmer Road, Bethesda, MD, 20814, USA
3 Department of Psychology, 226 Thach Hall, Auburn University, Auburn, AL, 36849, USA
4 Auburn University MRI Research Center, Department of Electrical & Computer Engineering, 570 Devall Drive, Auburn University, Auburn, AL, 36832, USA
5 Alabama Advanced Imaging Consortium, Auburn University and University of Alabama Birmingham, AL, USA
6 Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, 300 First Avenue, Harvard Medical School, Boston, MA 02129; & Home Base, A Red Sox Foundation and Massachusetts General Hospital Program; and Defense and Veterans Brain Injury Center, Bethesda, MD, USA
There is a high comorbidity of posttraumatic stress (PTS) and mild traumatic brain injury (mTBI), with largely overlapping symptomatology, in military service members.
To examine white matter integrity associated with PTS and mTBI as assessed using diffusion tensor imaging (DTI).
Seventy-four active-duty U.S. soldiers with PTS (n = 16) and PTS with co-morbid history of mTBI (PTS/mTBI; n = 28) were compared to a military control group (n = 30). Participants received a battery of neurocognitive and clinical symptom measures. The number of abnormal DTI values was determined (>2 SDs from the mean of the control group) for fractional anisotropy (FA) and mean diffusivity (MD), and then compared between groups. In addition, mean DTI values from white matter tracts falling into three categories were compared between groups: (i) projection tracts: superior, middle, and inferior cerebellar peduncles, pontine crossing tract, and corticospinal tract; (ii) association tracts: superior longitudinal fasciculus; and (iii) commissure tracts: cingulum bundle (cingulum-cingulate gyrus and cingulum-hippocampus), and corpus callosum.
The comorbid PTS/mTBI group had significantly greater traumatic stress, depression, anxiety, and post-concussive symptoms, and they performed worse on neurocognitive testing than those with PTS alone and controls. The groups differed greatly on several clinical variables, but contrary to what we hypothesized, they did not differ greatly on primary and exploratory analytic approaches of hetero-spatial whole brain DTI analyses.
The findings suggest that psychological health conditions rather than pathoanatomical changes may be contributing to symptom presentation in this population.
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