Effects of chronic mild traumatic brain injury on white matter integrity in Iraq and Afghanistan war veterans

• Published in: Human brain mapping Vol. 34; no. 11; pp. 2986 - 2999
• Main Authors: Morey, Rajendra A., Haswell, Courtney C., Selgrade, Elizabeth S., Massoglia, Dino, Liu, Chunlei, Weiner, Jonathan, Marx, Christine E., Cernak, Ibolja, McCarthy, Gregory
• Format: Journal Article
• Language: English
• Published: New York, NY Blackwell Publishing Ltd 01.11.2013; Wiley-Liss; John Wiley & Sons, Inc; John Wiley and Sons Inc
• Subjects: Adolescent; Adult; Afghan Campaign 2001; Aged; Biological and medical sciences; Brain - pathology; Brain Injuries - pathology; Brain Injuries - psychology; Brain Mapping; crossing fibers; Diffusion Tensor Imaging; Female; high angular resolution diffusion imaging; Humans; Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Iraq War, 2003-2011; Male; Medical sciences; Middle Aged; mild traumatic brain injury; Nerve Fibers - physiology; Nervous system; Neuropsychological Tests; posttraumatic stress disorder; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Radionuclide investigations; Regression Analysis; Stress Disorders, Post-Traumatic - psychology; Unconsciousness - complications; Unconsciousness - etiology; Veterans; white matter; Young Adult; Asia; Iraq; High resolution; Nervous system diseases; Radiodiagnosis; Central nervous system; crossing fibers; Diffusion imaging; War; Posttraumatic stress disorder; White matter; Trauma; high angular resolution diffusion imaging; mild traumatic brain injury; Encephalon; Veteran; white matter; posttraumatic stress disorder
• DOI: 10.1002/hbm.22117
• ISSN: 1065-9471

Mild traumatic brain injury (TBI) is a common source of morbidity from the wars in Iraq and Afghanistan. With no overt lesions on structural MRI, diagnosis of chronic mild TBI in military veterans relies on obtaining an accurate history and assessment of behavioral symptoms that are also associated with frequent comorbid disorders, particularly posttraumatic stress disorder (PTSD) and depression. Military veterans from Iraq and Afghanistan with mild TBI (n = 30) with comorbid PTSD and depression and non‐TBI participants from primary (n = 42) and confirmatory (n = 28) control groups were assessed with high angular resolution diffusion imaging (HARDI). White matter‐specific registration followed by whole‐brain voxelwise analysis of crossing fibers provided separate partial volume fractions reflecting the integrity of primary fibers and secondary (crossing) fibers. Loss of white matter integrity in primary fibers (P < 0.05; corrected) was associated with chronic mild TBI in a widely distributed pattern of major fiber bundles and smaller peripheral tracts including the corpus callosum (genu, body, and splenium), forceps minor, forceps major, superior and posterior corona radiata, internal capsule, superior longitudinal fasciculus, and others. Distributed loss of white matter integrity correlated with duration of loss of consciousness and most notably with “feeling dazed or confused,” but not diagnosis of PTSD or depressive symptoms. This widespread spatial extent of white matter damage has typically been reported in moderate to severe TBI. The diffuse loss of white matter integrity appears consistent with systemic mechanisms of damage shared by blast‐ and impact‐related mild TBI that involves a cascade of inflammatory and neurochemical events. Hum Brain Mapp 34:2986–2999, 2013. © 2012 Wiley Periodicals, Inc.