Long-term Trajectories of Depressive Symptoms in Deployed Military Personnel: A 10-year prospective study

Abstract

Background. Military missions are associated with an increased risk of depression. Understanding the long-term development of depressive symptoms after deployment is important to improve decision-making regarding deployment and mental health policies in the military. Therefore, this study aims to investigate trajectories of depressive symptoms from pre- to post-deployment and assess the role of specific factors, such as demographics, early life trauma, posttraumatic stress disorder (PTSD) symptoms and deployment stressors, in the Dutch army. Methods. The study includes a cohort of 1032 military men and women deployed to Afghanistan between 2005 and 2008. From pre- to 10 years post-deployment (across 6 distinct time points), depressive and PTSD symptoms were assessed using the Symptom CheckList-90 (SCL-90) and the Self-Rating Inventory for PTSD (SRIP) respectively. Demographics, early trauma, and deployment experiences were collected at baseline and after deployment, respectively. Latent Class Growth Analysis was used to explore heterogeneity in developmental trajectories of depressive symptoms over time. Results. The study identified four trajectories for depressive symptoms: resilient (65%), intermediate-stable (20%), symptomatic-chronic (9%), and late-onset-increasing (6%). The late-onset-increasing group had the highest proportion of individuals younger than 21 years. In addition, the resilient group was less likely to have experienced deployment stressors and the symptomatic-chronic group reported more early life traumas compared to the other groups. For individuals classified in trajectories with higher levels of depressive symptoms, PTSD symptoms were higher at all time points. Conclusions. Multiple trajectories for depressive symptoms were identified in a military sample up to 10 years after deployment. These trajectories were associated with age, early trauma, deployment stressors and PTSD symptoms. The majority of the sample fell within the resilient trajectory, supporting the notion that deployed military personnel possess a high level of resilience. Overall, these findings provide valuable insights and a foundation for further research in this area.