A Decade of War: Prospective Trajectories of Posttraumatic Stress Disorder Symptoms Among Deployed US Military Personnel and the Influence of Combat Exposure

Carrie J Donoho, George A Bonanno, Ben Porter, Lauren Kearney, Teresa M Powell

Post-traumatic stress disorder (PTSD) is a common psychiatric disorder among service members and veterans. The clinical course of PTSD varies across individuals, and patterns of symptom development have yet to be clearly delineated. Previous studies have been limited by convenience sampling, short follow-up periods, and inability to account for combat-related trauma. To determine the trajectories of PTSD symptoms among deployed military personnel with and without combat exposure, we used data from a population-based representative sample of 8,178 US service members participating in the Millennium Cohort Study from 2001-2011. Using latent class growth mixture modeling, trajectories of PTSD symptoms were determined in the total sample and in individuals with and without combat exposure. Four trajectories of PTSD were characterized: resilient, pre-existing, new-onset, and moderate-stable. Across all trajectories combat deployed service members diverged from non-combat deployed service members after a single deployment, and generally had higher PTSD symptoms. Based on the models, nearly 90% of those without combat and 80% of those with combat exposure remained resilient over the 10-year period. Findings demonstrate the clinical course of PTSD symptoms have heterogeneous patterns of development, but that combat exposure is uniformly associated with poorer mental health.