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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Psychiatry | doi: 10.3389/fpsyt.2018.00608

Posttraumatic stress disorder symptom network analysis in U.S. military veterans: Examining the impact of combat exposure

 Rachel D. Phillips1, 2*,  Sarah M. Wilson3, 4,  Delin Sun1, 2, Mid-Atlantic MIRECC Workgroup2 and Rajendra A. Morey1, 2, 4
  • 1Brain Imaging and Analysis Center, Duke University, United States
  • 2Durham VA Health Care System, United States
  • 3Durham Center for Health Services Research in Primary Care, Durham VA Health Care System, United States
  • 4Department of Psychiatry and Behavioral Sciences, School of Medicine, Duke University, United States

Recent work inspired by graph theory has begun to conceptualize mental disorders as networks of interacting
symptoms. Posttraumatic stress disorder (PTSD) symptom networks have been investigated in clinical samples
meeting full diagnostic criteria, including military veterans, natural disaster survivors, civilian survivors of war, and
child sexual abuse survivors. Despite reliable associations across reported networks, more work is needed to
compare central symptoms across trauma types. Additionally, individuals without a diagnosis who still experience
symptoms, also referred to as subthreshold cases, have not been explored with network analysis in veterans. A
sample of 1,050 Iraq/Afghanistan-era U.S. military veterans (851 males, mean age=36.3, SD=9.53) meeting current
full-criteria PTSD (n=912) and subthreshold PTSD (n=138) were assessed with the Structured Clinical Interview for
DSM-IV Disorders (SCID). Combat Exposure Scale (CES) scores were used to group the sample meeting full criteria
into high (n=639) and low (n=273) combat exposure subgroups. Networks were estimated using regularized
partial correlation models in the R-package qgraph, and robustness tests were performed with bootnet. Frequently
co-occurring symptom pairs (strong network connections) emerged between two avoidance symptoms,
hypervigilance and startle response, loss of interest and detachment, as well as detachment and restricted affect.
These associations replicate findings reported across PTSD trauma types. A symptom network analysis of
subthreshold PTSD in a veteran population found significantly greater overall connectivity in the full-criteria PTSD
group as compared to the symptom network in the subthreshold PTSD group. Additionally, novel findings indicate
that the association between intrusive thoughts and irritability is a feature of the symptom networks of veterans with
high levels of combat exposure. Mean node predictability is high for PTSD symptom networks, averaging 51.5%
shared variance. With the tools described here and by others, researchers can help refine diagnostic criteria for
PTSD, develop more accurate measures for assessing PTSD, and eventually inform therapies that target symptoms
with strong network connections to interrupt interconnected symptom complexes and promote functional recovery.

Keywords: Symptom network, PTSD (post traumatic stress disorder), Veterans, Combat exposure, subthreshold, Trauma

Received: 20 Sep 2018; Accepted: 30 Oct 2018.

Edited by:

Alexandre Heeren, Université Catholique de Louvain, Belgium

Reviewed by:

Payton J. Jones, Harvard University, United States
Giovanni Briganti, Free University of Brussels, Belgium  

Copyright: © 2018 Phillips, Wilson, Sun, Workgroup and Morey. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Ms. Rachel D. Phillips, Brain Imaging and Analysis Center, Duke University, Durham, United States,