Altered amygdala activation during face processing in Iraqi and Afghanistani war veterans

Twelve men with PTSD related to combat in Operations Enduring Freedom and/or Iraqi Freedom, 12 male combat-exposed control patients with a history of Operations Enduring Freedom and/or Iraqi Freedom combat exposure but no history of PTSD, and 12 healthy control male patients with no history of combat exposure or PTSD completed a face-matching task during functional magnetic resonance imaging.The PTSD group showed greater amygdala activation to fearful versus happy faces than both the combat-exposed control and healthy control groups. Both the PTSD and the combat-exposed control groups showed greater amygdala activation to all faces versus shapes relative to the healthy control group. However, the combat-exposed control group relative to the PTSD group showed greater prefrontal/parietal connectivity with the amygdala, while the PTSD group showed greater connectivity with the subgenual cingulate. The strength of connectivity in the PTSD group was inversely related to avoidance scores.These observations are consistent with the hypothesis that PTSD is associated with a deficiency in top-down modulation of amygdala activation by the prefrontal cortex and shows specific sensitivity to fearful faces.Soldiers exposed to combat in Operations Iraqi Freedom (OIF) and Enduring Freedom (OEF) are at high risk for post-traumatic stress disorder (PTSD) [1]. PTSD is an aversive reaction to a life-threatening, emotionally salient event [2] that is associated with increased mortality and morbidity [3]. The majority of those who experience such an event have a substantial stress response [4] that is characterized by activation in physiological and neuroendocrine systems [5-8]. Such stress responses are associated with hyperactivation in the insula and amygdala [9,10] brain structures that are involved in processing emotional information. Amygdala activation has been strongly linked to negative affective states in fear processing [11-13] and PTSD [14-17]. A number of studies have succes