Symptoms of Posttraumatic Stress Rather Than Mild Traumatic Brain Injury Best Account for Altered Emotional Responses in Military Veterans.Emotional dysfunction is evident in posttraumatic stress disorder (PTSD), yet it is unclear what aspects of the disorder most directly relate to aberrant emotional responding.  Also, the frequent co-occurrence of blast-related mild traumatic brain injuries (mTBIs) among recently deployed U.S. military personnel complicates efforts to understand the basis for emotional disruption.  We studied a cross-sectional sample (enriched for PTSD and mTBI) of 123 U.S. veterans of wars in Iraq and Afghanistan.  We measured subjective affective evaluations and peripheral psychophysiological responses to images with pleasant, neutral, unpleasant, and combat-related aversive content.  When compared with other postdeployment participants, those who had combat-related PTSD rated pleasant image content as less positive (ηp2 = .04) and less arousing (ηp2 = .06), and exhibited heightened physiological responsivity to combat image content (ηp2 = .07).  Symptoms of PTSD were associated with elevated skin conductance responses (β = .28), reduced heart rate deceleration (β = .44 to .47), and increased corrugator facial muscle electromyography (β = .47).  No effects for blast-related mTBI were observed across any affective modulation measures.  These findings point to a greater impact of PTSD symptomatology than blast-related mTBI on emotional functioning and highlight the utility of dimensional assessments of psychopathology for understanding the effects of combat-stress conditions on adjustment to civilian life.
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