The aim of this study was to examine neuropsychological functioning and white matter integrity, in service members and veterans (SMVs) after mild traumatic brain injury (MTBI), with versus without post-traumatic stress disorder (PTSD). Participants were 116 U.S. military SMVs, prospectively enrolled from the Walter Reed National Military Medical Center (Bethesda, MD), who had sustained an MTBI (n = 86) or an injury without TBI (i.e., Injured Control [IC]; n = 30). Participants completed a battery of neuropsychological measures (neurobehavioral and -cognitive), as well as diffusion tensor imaging (DTI) of the brain, on average 6 years post-injury. Based on diagnostic criteria for PTSD, participants in the MTBI group were classified into two subgroups: MTBI/PTSD-Present (n = 21) and MTBI/PTSD-Absent (n = 65). Participants in the IC group were included only if they were classified as PTSD-Absent. The MTBI/PTSD-Present group had a significantly higher number of self-reported symptoms on all neurobehavioral measures (e.g., depression), and lower scores on more than half of the neurocognitive domains (e.g., processing speed), compared to the MTBI/PTSD-Absent and IC/PTSD-Absent groups. There were no significant group differences for the vast majority of DTI measures, with the exception of a handful of regions (i.e., superior longitudinal fascicle and superior thalamic radiation). These results suggest that there is 1) a strong relationship between PTSD and poor neuropsychological outcome after MTBI and 2) a lack of a relationship between PTSD and white matter integrity, as measured by DTI, after MTBI. Concurrent PTSD and MTBI should be considered a risk factor for poor neuropsychological outcome that requires early intervention.
Keywords: diffusion tensor imaging; mild traumatic brain injury; neuropsychological assessment; post-traumatic stress.