Predictors of Risk and Resilience for Posttraumatic Stress Disorder Among Ground Combat Marines: Methods of the Marine Resiliency Study

Abstract

The Marine Resiliency Study (MRS) is a prospective study of factors predictive of posttraumatic stress disorder (PTSD) among approximately 2,600 Marines in 4 battalions deployed to Iraq or Afghanistan. We describe the MRS design and predeployment participant characteristics. Starting in 2008, our research team conducted structured clinical interviews on Marine bases and collected data 4 times: at predeployment and at 1 week, 3 months, and 6 months postdeployment. Integrated with these data are medical and career histories from the Career History Archival Medical and Personnel System (CHAMPS) database. The CHAMPS database showed that 7.4% of the Marines enrolled in MRS had at least 1 mental health diagnosis. Of enrolled Marines, approximately half (51.3%) had prior deployments. We found a moderate positive relationship between deployment history and PTSD prevalence in these baseline data.

Genomic predictors of combat stress vulnerability and resilience in U.S. Marines: A genome-wide association study across multiple ancestries implicates PRTFDC1 as a potential PTSD gene

“…Participants were recruited from the MRS, a large, prospectively assessed cohort of Marines and Sailors with index deployments to Iraq or Afghanistan (Baker et al, 2012). This all-male study included 3494 subjects exposed to a DSM-IV criteria A1 traumatic event and represents one of the largest and most homogenous PTSD GWAS to date.…”

“…For example, this has been found for childhood trauma (Binder et al, 2008) as well as adult trauma such as combat exposure (Lyons et al, 2013). The thoroughly characterized MRS includes pre-and postcombat exposure trauma assessments, allowing for detailed testing of GxE interactions.…”

“…Participants were recruited from two studies including military personnel: (1) the Marine Resiliency Study, a prospective PTSD study with longitudinal follow-up (pre-and post-exposure to combat stress) of U.S. Marines bound for deployment to Iraq or Afghanistan (Baker et al, 2012) (here referred to as MRS-I), and (2) the Marine Resiliency Study-II (MRS-II), which followed a very similar protocol. The protocols were approved by the University of California -San Diego Institutional Review Board, and all participants provided written informed consent to participate.…”

“…Most research has focused on: (1) the hypothalamic-pituitary-adrenal (HPA) axis, (2) the ascending brainstem locus coeruleus noradrenergic system, and (3) the limbic amygdalar frontal pathway mediating fear processing. Among the over 25 PTSD candidate genes currently reported (Amstadter et al, 2009(Amstadter et al, , 2011Binder et al, 2008;Boscarino et al, 2011;Cao et al, 2013;Comings et al, 1996;Dragan and Oniszczenko, 2009;Gillespie et al, 2013;Goenjian et al, 2012;Grabe et al, 2009;Guffanti et al, 2013;Hauer et al, 2011;Kolassa et al, 2010;Logue et al, 2013a,b;Lyons et al, 2013;Mellman et al, 2009;Nelson et al, 2009;Ressler et al, 2011;Segman et al, 2002;Solovieff et al, 2014;Voisey et al, 2010;Wilker et al, 2013;Xie et al, 2013), promising findings include associations of PTSD symptoms with the serotonin transporter gene (SERT, SLC6A4) (Xie et al, 2009), which is linked to depression and anxiety disorders, as well as differential acquisition of conditioned fear and increased amygdala excitability in humans. In addition, FKBP5, a co-chaperone of the glucocorticoid receptor involved in the HPA axis, has a significant interaction with severity of child abuse in the prediction of adult PTSD symptoms, indicating a gene by environment (GxE) interaction (Binder et al, 2008).…”

“…The MRS is a well-characterized, prospective study of Marines and Sailors scheduled for combat deployment to Iraq or Afghanistan, with longitudinal follow-up to track the effect of combat stress (Baker et al, 2012). This young, all-male military cohort is among the largest and most homogenous of PTSD studies available and presents a unique resource to test mechanisms of risk that mediate the link between stressor exposure and outcome, or that moderate or synergize with exposure to mitigate or exacerbate its effect over time.…”