Combat-related posttraumatic stress disorder and longitudinal hyper-responsivity to trauma-related visual stimuli: stability over 2 years

Abstract

Introduction: Soldiers with combat-related posttraumatic stress disorder (PTSD) show survival-mode functioning, implying generalized hyper-arousal along with a memory bias for trauma-related stimuli. To date, a precise spatiotemporal characterization of maladaptive neurophysiological responses underlying experiential trauma reminders in PTSD is lacking. We used magnetoencephalography to investigate rapid evoked responses during visual processing and delayed recognition of war-related versus neutral pictures in soldiers with PTSD and trauma-exposed peers who did not develop PTSD. Methods: The sample consisted of 24 soldiers with PTSD who had served in Afghanistan and 28 war-exposed soldiers without PTSD, matched for combat exposure, military experience, and rank. We completed longitudinal follow-up studies 2 years later with 35 of these same soldiers, 13 with PTSD and 22 control participants. We analysed brain activation evoked by visual processing and delayed recognition tasks that involved both war-related and neutral pictures, and we used a mixed-effects model to determine whether changes in activity occurred between the two test periods. Results: In the visual processing task, soldiers with PTSD showed rapid-onset and sustained hyper-activation for war-related imagery in the left temporal pole and superior frontal gyrus and the right calcarine. In contrast, control soldiers exhibited greater activity for war-related imagery in the left temporal–parietal junction and right inferior frontal gyrus. In the delayed recognition task, both groups showed increased activity in occipital cortices for war images compared with neutral images. A crucial finding was that, compared with control participants, the PTSD group also showed elevated and sustained activation in limbic areas for war imagery. Discussion: These results characterize the evoked neurophysiology underlying hyper-responsivity found in soldiers with PTSD at the juncture of stress and memory in contrast to their trauma-exposed peers without PTSD.