A multimodal imaging study in US veterans of Operations Iraqi and Enduring Freedom with and without major depression after blast-related concussion
Veterans Affairs San Diego Healthcare System, USA. NeuroImage
(Impact Factor: 6.36).
05/2010; 54 Suppl 1:S69-75. DOI: 10.1016/j.neuroimage.2010.04.269
Although the exact number of affected individuals is unknown, it has been estimated that approximately 20% of U.S. veterans of Operations Enduring Freedom (OEF) and Iraqi Freedom (OIF) have experienced mild traumatic brain injury (mTBI) (i.e., concussion), which is defined as a brief loss or alteration of consciousness from a blow or jolt to the head. Blast exposure is among the most common causes of concussion in OEF-OIF warriors. Although the mechanism is unknown, major depressive disorder (MDD) after head injury is common. The purpose of this study was to use diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) to examine the structural and functional neural correlates of MDD in OEF-OIF combat veterans with a self-reported history of blast-related concussion. We hypothesized that subjects in the MDD group (i.e., individuals with a history of blast-related concussion who were experiencing current MDD) relative to individuals in the non-MDD group (i.e., individuals with a history of blast-related concussion but no current or lifetime history of MDD) would show amygdala hyperactivity and disruption of white matter tracts connecting prefrontal and limbic brain regions. To test these hypotheses, 11 MDD and 11 non-MDD individuals underwent DTI and performed a validated emotional face matching task during fMRI. MDD relative to non-MDD individuals showed greater activity during fear matching trials in the amygdala and other emotion processing structures, lower activity during fear matching trials in emotional control structures such as the dorsolateral prefrontal cortex and lower fractional anisotropy (FA) in several white matter tracts including the superior longitudinal fasciculus (SLF). Greater depressive symptom severity correlated negatively with FA in the SLF. These results suggest a biological basis of MDD in OEF-OIF veterans who have experienced blast-related concussion, and may contribute to the development of treatments aimed at improving the clinical care of this unique population of wounded warriors.
Available from: Alison M Cogan
- "No significant differences with diagnosis of PTSD or major depression. Matthews et al. 2011 22 (11 with concurrent MDD) MDD group had significantly lower FA in corona radiata, corpus callosum, and superior longitudinal fasciculus. Greater depressive symptoms inversely correlated with FA in the superior longitudinal fasciculus. "
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ABSTRACT: Mild traumatic brain injury (mTBI) has been labeled the “signature injury” of the wars in Iraq and Afghanistan, and approximately half of mTBIs that occur in combat are due to explosive blasts. The rapid change in pressure that results from an explosion may make blast injury distinct from mTBI due to other causes. Persistent symptoms following blast mTBI may be related to white matter damage that has recently been identified using innovative neuroimaging techniques, such as diffusion tensor imaging (DTI). By comparing the DTI findings in blast mTBI to studies of the effects of white matter structure on functional performance, hypotheses can be developed about the implications of the injury for engagement in occupation. Incorporation of neuroscience evidence about the effects of blast mTBI may provide objective evidence of underlying damage that correlates with deficits in occupational engagement of military service members and veterans who are affected by these injuries.
Available from: Mary R Newsome
- "These changes appeared to be persistent in a subgroup (N=47) of these Service Members who underwent follow-up imaging 6–12 months later. Matthews et al. 2011b Patients: 11 mTBI w/ MDD (11M, 0F) "
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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.
Available from: Kevin KW Wang
- "Recent advances and the emergence of newer functional imaging techniques such as Diffusion Tensor Imaging (DTI), fl uorodeoxyglucose positron emission tomography (FDG-PET), Single Photon Emission Computed Tomography (SPECT) and functional Magnetic Resonance Imaging (fMRI) have shown great potential in detecting brain tissue damage that are invisible in CT and MRI. These newer technologies therefore, may have a signifi cant potential in diagnosing mTBI in future (Brenner, 2011; Matthews et al., 2011). The availability of these imaging tools, however, is very limited and will require further experimental validation and correlation with the neurophysiological paradigms of TBI. "
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