UC San Diego

Background: Posttraumatic stress disorder (PTSD) results from experiencing or witnessing traumatic, life- threatening events including military combat. There is concern about the health impact of military deployment to Iraq and Afghanistan after reports of higher prevalence of PTSD in combat-exposed veterans. Further, the vulnerability or resiliency for PTSD symptoms in individuals following overwhelming stress is not well understood. Methods: Using data from a large population- based military cohort, the Millennium Cohort Study baseline (July 2001 - June 2003) and follow-up (June 2004 - February 2006), the objective of this dissertation was to 1) document the prevalence of PTSD symptoms and diagnosis, associated physical and mental health, and the association with self-reported exposure to chemical and biological warfare agents independent of other combat- related exposures, 2) prospectively investigate the effect of military deployment and self-reported combat exposures on new-onset and persistent PTSD symptoms, and 3) prospectively investigate the association of prior assault and new-onset PTSD symptoms among combat deployed. : At baseline, the combined weighted prevalence PTSD symptoms in the Millennium Cohort was 3.6%, with the majority (2.0%) being those with PTSD symptoms without a diagnosis. Nearly 25% of the Cohort deployed between baseline and follow-up. New-onset PTSD symptoms or diagnoses were identified in 7.6%-8.7% of deployers reporting combat exposures, 1.4%-2.1% of deployers not reporting combat exposures, and 2.3%-3.0% of nondeployers. Persistence of PTSD symptoms was similar in nondeployed and those deployed with combat exposures. New-onset PTSD symptoms or diagnosis among deployers reporting combat exposures was 21.7% for women reporting prior assault and 10.1% for women not reporting prior assault. Among men, the rates were 12.4% and 5.9% respectively. Conclusions: These data suggest a 2% prevalence of PTSD symptoms without diagnosis and a threefold increase in new-onset PTSD symptoms or diagnosis among deployed military personnel reporting combat exposures. Further, these prospective data indicate a two-fold increase in new-onset PTSD symptoms or diagnosis among deployed military personnel reporting combat exposures who reported a prior assault at baseline. The findings of this dissertation define the vulnerability of some individuals to new-onset PTSD symptoms and emphasize that specific combat exposures, rather than deployment itself, significantly affect the onset of PTSD symptoms postdeployment