Growth mixture modeling of post-combat aggression: Application to soldiers deployed to Iraq

Prior research has found substantial heterogeneity in the course of key post-deployment outcomes, such as PTSD. The current paper employs growth mixture modeling to identify differential trajectories of change in the course of post-combat aggression. A Brigade Combat Team completed surveys within 72 h of return from an Iraq deployment, 4 months later, and at 12 months after return. Based on model fit indices, analyses yielded four latent aggression trajectories: “low-stable”, “delayed”, “recovery”, and “chronic”. In addition, most individuals aligned with a “low-stable” trajectory indicative of minimal aggression in the first year following return from a combat deployment. A conditional model showed that lower posttraumatic stress and lower combat exposure characterized individuals aligned with the “low-stable” aggression trajectory relative to individuals aligned with “chronic” and “delayed” aggression trajectories. Implications for targeted intervention and future research are discussed.