Electrocortical processing of social signals of threat in combat-related post-traumatic stress disorder

• Combat-exposed veterans with and without PTSD performed a face-matching task.
• VPPs elicited by emotional faces were smaller for veterans with PTSD.
• Angry faces elicited smaller LPPs for veterans with PTSD.
• Angry faces also had a more negative effect on accuracy for veterans with PTSD.
• Social signals of direct threat are processed abnormally in combat-related PTSD.

Post-traumatic stress disorder (PTSD) is characterized by avoidance, emotional numbing, increased arousal and hypervigilance for threat following a trauma. Thirty-three veterans (19 with PTSD, 14 without PTSD) who had experienced combat trauma while on deployment in Iraq and/or Afghanistan completed an emotional faces matching task while electroencephalography was recorded. Vertex positive potentials (VPPs) elicited by happy, angry and fearful faces were smaller in veterans with versus without PTSD. In addition, veterans with PTSD exhibited smaller late positive potentials (LPPs) to angry faces and greater intrusive symptoms predicted smaller LPPs to fearful faces in the PTSD group. Veterans with PTSD were also less accurate at identifying angry faces, and accuracy decreased in the PTSD group as hyperarousal symptoms increased. These findings show reduced early processing of emotional faces, irrespective of valence, and blunted prolonged processing of social signals of threat in conjunction with impaired perception for angry faces in PTSD.