Assessment of Neuropsychological Function in Veterans with Blast-related Mild Traumatic Brain Injury and Sub-concussive Blast Exposure

Abstract Objective: Nearly 20% of Veterans report deployment-related traumatic brain injury (TBI) with most deployment injuries stemming from blast exposure. While Veterans with TBI report cognitive complaints and may acutely display impaired neuropsychological performance, there is little evidence examining the effects of so-called sub-concussive blast exposure, which does not meet clinical symptom criteria for mild TBI during the acute period following exposure. We compared chronic effects of combat blast-related mild TBI and combat-related sub-concussive injuries on neuropsychological performance in Veterans.Methods: Post-9/11 Veterans with sub-concussive (n=33) and mild TBI (n=26) from combat-related blast-exposure in addition to and without control Veterans (n=33) without combat-related blast-exposure, completed neurocognitive assessments of intellectual and executive functioning, processing speed, response inhibition, and working memory via NIH toolbox. Veterans also completed assessment of current clinical psychopathology. The Quantification of Cumulative Blast Exposure was used to assess the number of blast exposure and their severity as well as non-blast-related head injuries. Veteran’s self-reported their history of non-blast head injuries and current medication. Huber Robust Regressions were employed to compare neuropsychological performance across groups. Results: Veterans with combat-related mild TBI and sub-concussive blast exposure displayed significantly poorer performance on measures of processing speed compared to controls. After adjusting for PTSD symptoms, those with combat-related mild TBI exhibited slower processing speed than controls; however, this result was not statistically significant after FDR correction.Conclusion: Veterans in the mild TBI group exhibited poorer processing speed and working memory relative to controls even when controlling for PTSD. However, cognition did not significantly differ between the sub-concussive and control groups or between sub-concussive and mild TBI groups. These results suggest that traditional cognitive assessment may not be sensitive enough to detect long-term effects of sub-concussive blast exposure.