Approximately 275,000 American service members deployed to Iraq or Afghanistan have sustained a mild traumatic brain injury (mTBI), with 75% of these incidents involving an explosive blast. Combat-related mTBI is frequently associated with comorbid mental health disorders, especially posttraumatic stress disorder (PTSD). Attention problems, including sustained attention, are common cognitive complaints of veterans with TBI and PTSD. The present study sought to examine neural correlates of sustained attention in veterans with blast mTBI and/or current PTSD. In 124 veterans of Operations Enduring and Iraqi Freedom (OEF/OIF), we examined event-related potentials (ERPs) elicited by targets and non-targets during performance of a degraded-stimulus continuous performance task (DS-CPT). Four groups, consisting of veterans with blast-related mTBI only, current PTSD only, both blast mTBI and PTSD, and a control group, were studied. Compared to all other groups, blast mTBI only participants were more likely to respond regardless of stimulus type during the DS-CPT. During target detection, the three mTBI/PTSD groups showed reduced amplitude of the P3b (i.e., P300) ERP at Pz compared to the control group. P3b of the three affected groups did not differ from each other. These results suggest that parietal P3b amplitude reduction during target detection in the DS-CPT task may be an index of brain pathology after combat trauma, yet the diminished brain response fails to differentiate independent effects of blast-related mTBI or severity of PTSD symptomatology.
Bibliographical noteFunding Information:
This work was supported by grants to Scott R. Sponheim from the Congressionally Directed Medical Research Program ( W81XWH-08-2-0038 ), the Minnesota Veterans Research Institute (MVRI) , and the Rehabilitation Research and Development Service of the VA Office of Research and Development (Award Number 1I01RX000622 ). This work was also supported by the National Science Foundation Graduate Research Fellowship to Craig A. Marquardt (Grant Number 00039202 ). Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the Department of Defense, the Department of Veterans Affairs, or the National Science Foundation. The authors wish to thank the U.S. military veterans whose participation made this work possible.
- Degraded stimulus-continuous performance task
- Mild TBI