White Matter Abnormalities in Veterans With Mild Traumatic Brain Injury

Department of Child and Adolescent Psychiatry, Erasmus Universiteit Rotterdam, Rotterdam, South Holland, Netherlands
American Journal of Psychiatry (Impact Factor: 12.3). 12/2012; 169(12):1284-91. DOI: 10.1176/appi.ajp.2012.12050600
Source: PubMed


It has been estimated that 10%-20% of U.S. veterans of the wars in Iraq and Afghanistan experienced mild traumatic brain injury (TBI), mostly secondary to blast exposure. Diffusion tensor imaging (DTI) may detect subtle white matter changes in both the acute and chronic stages of mild TBI and thus has the potential to detect white matter damage in patients with TBI. The authors used DTI to examine white matter integrity in a relatively large group of veterans with a history of mild TBI.

DTI images from 72 veterans of the wars in Iraq and Afghanistan who had mild TBI were compared with DTI images from 21 veterans with no exposure to TBI during deployment. Conventional voxel-based analysis as well as a method of identifying spatially heterogeneous areas of decreased fractional anisotropy ("potholes") were used. Veterans also underwent psychiatric and neuropsychological assessments.

Voxel-based analysis did not reveal differences in DTI parameters between the veterans with mild TBI and those with no TBI. However, the veterans with mild TBI had a significantly higher number of potholes than those without TBI. The difference in the number of potholes was not influenced by age, time since trauma, a history of mild TBI unrelated to deployment, or coexisting psychopathology. The number of potholes was correlated with the severity of TBI and with performance in executive functioning tasks.

Veterans who had blast-related mild TBI showed evidence of multifocal white matter abnormalities that were associated with severity of the injury and with relevant functional measures. Overall, white matter potholes may constitute a sensitive biomarker of axonal injury that can be identified in mild TBI at acute and chronic stages of its clinical course.

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Available from: Ricardo E. Jorge, Aug 14, 2015
    • "the bulk of studies examining military blast mTBI have included individuals with both primary blast exposure and additional secondary and tertiary injuries . These studies have generally shown decreases in white matter integrity both in the subacute ( Mac Donald et al . , 2011 ) and chronic phase ( Davenport et al . , 2012 ; Hayes et al . , 2015 ; Jorge et al . , 2012 ; Mac Donald et al . , 2011 ; Morey et al . , 2013 ) , similar to the civilian mTBI literature ( but see Bazarian et al . , 2013 ; Levin et al . , 2010 ; Watts et al . , 2014 ) . However , findings of greater neurologic deficits in individuals exposed to combat - related mTBI than civilian mTBI ( Ruff et al . , 2012 ) provide some evide"
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    • "In addition, recent results in animal models and humans suggest that DTI indices in GM might reveal important information about mTBI, but most DTI analysis tools available today concentrate only on the analysis of the white matter (Budde et al. 2011; Bouix et al. 2013). Recent techniques have tried to address this problem by creating full brain subject-specific profiles of injury based on a reference atlas built from healthy subjects (Bouix et al. 2013; Kim et al. 2013; Mayer et al. 2014; Jorge et al. 2012; Davenport et al. 2015). This issue is even more interesting in military population with blast exposure where one could expect both subject specific abnormalities and a common pattern of injury from exposure to blast. "
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    ABSTRACT: Traumatic brain injury (TBI) remains one of the most prevalent forms of morbidity among Veterans and Service Members, particularly for those engaged in the conflicts in Iraq and Afghanistan. Neuroimaging has been considered a potentially useful diagnostic and prognostic tool across the spectrum of TBI generally, but may have particular importance in military populations where the diagnosis of mild TBI is particularly challenging, given the frequent lack of documentation on the nature of the injuries and mixed etiologies, and highly comorbid with other disorders such as post-traumatic stress disorder, depression, and substance misuse. Imaging has also been employed in attempts to understand better the potential late effects of trauma and to evaluate the effects of promising therapeutic interventions. This review surveys the use of structural and functional neuroimaging techniques utilized in military studies published to date, including the utilization of quantitative fluid attenuated inversion recovery (FLAIR), susceptibility weighted imaging (SWI), volumetric analysis, diffusion tensor imaging (DTI), magnetization transfer imaging (MTI), positron emission tomography (PET), magnetoencephalography (MEG), task-based and resting state functional MRI (fMRI), arterial spin labeling (ASL), and magnetic resonance spectroscopy (MRS). The importance of quality assurance testing in current and future research is also highlighted. Current challenges and limitations of each technique are outlined, and future directions are discussed.
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    • "However, PTSD symptom severity was not associated with white matter alterations. Several other studies have reported similar negative findings [Jorge et al., 2012; Morey et al., 2012; Taber et al., 2015] although two studies using different diffusion metrics suggest white matter involvement in PTSD [Bazarian et al., 2012; Davenport et al., 2015]. Nonetheless, PTSD-related neuropathology appears to be associated primarily with changes in gray matter volume [Bremner et al., 1995; Corbo et al., 2005; Kasai et al., 2008; O'Doherty et al., 2015; Smith, 2005] and functional alterations [Bremner et al., 1999; Daniels et al., 2010; Hayes et al., 2011; Milad et al., 2009; Sadeh et al., 2015; Shin and Liberzon , 2010; Shin et al., 2004; St Jacques et al., 2013; van Wingen et al., 2012]. "
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