Neural differences underlying face processing in veterans with TBI and co-occurring TBI and PTSD

Abstract Background Traumatic brain injury (TBI) is common in military personnel and associated with high rates of posttraumatic stress disorder (PTSD). TBI impacts widely-distributed neural patterns, some of which influence affective processing. Better understanding how TBI and PTSD/TBI alters affective neural activity may improve our understanding of comorbidity mechanisms, but to date the neural correlates of emotional processing in these groups has been relatively understudied. Methods Military controls, military personnel with a history of TBI, and military personnel with both TBI and PTSD (N = 53) completed an emotional face processing task during fMRI. Whole-brain activation and functional connectivity during task conditions were compared between groups. Results Few whole-brain group differences emerged in planned pairwise contrasts, though the TBI group showed some areas of hypoactivation relative to other groups during processing of faces versus shapes. The PTSD/TBI group compared to the control and TBI groups demonstrated greater connectivity between the amygdala and insula seed regions and a number of prefrontal and posterior cingulate regions. Limitations Generalizability to other patient groups, including those with only PTSD, has not yet been established. Conclusion TBI alone was associated with hypoactivation during a condition processing faces versus shapes, but PTSD with TBI was associated altered functional connectivity between amygdala and insula regions and cingulate and prefrontal areas. Altered connectivity patterns across groups suggests that individuals with PTSD/TBI may need to increase frontal connectivity with the insulae in order to achieve similar task-based activity.