White-matter alterations are associated with cognitive dysfunction decades following moderate-to-severe traumatic brain injury and/or post-traumatic stress disorder.

Mohamed, Abdalla Z.; Cumming, Paul; Nasrallah, Fatima A.

Background Possible white matter (WM) alterations following moderate-to-severe TBI and post-traumatic stress disorder (PTSD) and their relationship to clinical outcome have yet to be investigated decades post trauma. We utilized structural MRI and diffusion tensor images to investigate brain volume and WM alterations in Vietnam War veterans with moderate-severe TBI and/or PTSD examined five decades post-trauma. Methods Data from 160 veterans with history of moderate-to-severe TBI (n = 23), TBI+PTSD (n = 36), PTSD (n = 53), and control veterans (n = 48) were obtained from the Department of Defense Alzheimer’s Disease Neuroimaging Initiative database. Voxel-based morphometry and tract-based spatial statistics were used to investigate ongoing brain morphometry and WM abnormalities. The fractional anisotropy (FA) and mean diffusivity were then correlated with neuropsychological scores and amyloid deposition in the trauma groups. Results Compared to controls, the three trauma groups showed grey-matter atrophy, lower FA, and distinctly higher diffusivity in the major WM tracts included the corpus callosum, external and internal capsules, cingulum, inferior and superior longitudinal fasciculi. The FA and mean diffusivity correlated with the cognitive deficits in the trauma groups. Furthermore, the FA in the cingulum correlated negatively with amyloid deposition in the posterior cingulate cortex of all three trauma groups. Conclusion DTI detected WM abnormalities that correlated with the severity of present cognitive dysfunction and the degree of cortical amyloid deposition decades following moderate-to-severe TBI and/or PTSD. These results may hint that PTSD secondary to TBI may incur late cognitive sequalae and persistence of brain microstructures alterations.