title: Psychophysiological Investigation of Combat Veterans with Subthreshold Post-traumatic Stress Disorder Symptoms.
abstract: Military service members (SMs) with subthreshold combat-related post-traumatic stress disorder (PTSD) symptoms often have clinically significant functional impairment, even though they do not meet full PTSD criteria. We therefore assessed the psychophysical responses of SMs, upon their return from Afghanistan or Iraq, to a fear conditioning paradigm to better understand the biological underpinnings of symptom severity.
  
  
  
  Heart rate (HR), skin conductance, electromyography startle, and respiratory rate (RR) were monitored throughout three distinct phases of the paradigm-fear acquisition, fear inhibition, and fear extinction-while plasma catecholamines (epinephrine, norepinephrine, and dopamine) were measured at the end of fear inhibition.
  
  
  
  Those with higher PTSD symptom severity demonstrated elevations in HR and startle response to danger cues; elevated self-reported depression and anxiety; impaired functional status; poor skin conductance discrimination between danger and safety; and increases in HR and RR during fear extinction. Moreover, an inverse relationship was seen between plasma dopamine and HR during fear inhibition for those with high symptoms.
  
  
  
  Overall, the physiological responses we observed in our subthreshold PTSD population parallel what has been previously observed in full PTSD, making a case for addressing subthreshold PTSD symptoms in combat veterans.
authors.affiliation: Department of Medicine and Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814.
authors.forename: Michelle
authors.initials: M
authors.lastname: Costanzo
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 201 Dowman Drive, Atlanta, GA 30322.
authors.forename: Tanja
authors.initials: T
authors.lastname: Jovanovic
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 201 Dowman Drive, Atlanta, GA 30322.
authors.forename: Seth D
authors.initials: SD
authors.lastname: Norrholm
authors.affiliation: National Intrepid Center of Excellence, Walter Reed National Military Medical Center, 8901 Rockville Pike, Bethesda, MD 20889.
authors.forename: Rochelle
authors.initials: R
authors.lastname: Ndiongue
authors.affiliation: Department of Research Programs, Walter Reed National Military Medical Center, 8901 Rockville Pike, Bethesda, MD 20889.
authors.forename: Brian
authors.initials: B
authors.lastname: Reinhardt
authors.affiliation: Department of Medicine and Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Roy
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004298:Dopamine / Q000032:analysis / Q000097:blood; D004576:Electromyography / Q000379:methods; D004837:Epinephrine / Q000032:analysis / Q000097:blood; D005239:Fear / Q000523:psychology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000032:analysis / Q000097:blood; D011594:Psychometrics / Q000295:instrumentation / Q000379:methods; D013216:Reflex, Startle / Q000502:physiology; D056152:Respiratory Rate / Q000502:physiology; D013313:Stress Disorders, Post-Traumatic / Q000145:classification* / Q000523:psychology*; D011795:Surveys and Questionnaires; D014481:United States; D014493:United States Department of Veterans Affairs / Q000458:organization & administration; D014728:Veterans / Q000523:psychology*
chemical_list: D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine