Impact of Childhood Trauma and Warzone Moral Injury on Loneliness During Combat Deployment

Abstract
Loneliness predicts mental health problems and suicide in active duty solider (Cacioppo et al., 2016) and has been associated with a variety of distal and proximal relational factors, including early childhood trauma, perceived platoon support, and contact with friends and families. Recent longitudinal work with older U.S. military veterans suggests that adverse childhood experiences are a significant risk factor for persons with high-increasingly loneliness trajectories (Ong et al., 2024). Less is known about how civilian trauma across the lifespan and type of warzone trauma exposure (witnessing, personal threat, moral injury) uniquely predict loneliness during combat deployment, considering other relational risk and protective factors. To address this gap, this study utilized data from two waves of a cross-sectional post-deployment survey of Norwegian military personnel deployed to Afghanistan (N =6,939), administered eight years apart (2012 and 2020). The average time since deployment at the time of the survey was 5.15 years (SD = 2.46, range 1-10 years). Regression analyses indicated that serious life events experienced prior to age 18 (β = .04, p = .025) and the perpetration of morally injurious events during combat (β = .07, p < .001) were associated with higher levels of reported loneliness, whereas unit social cohesion (β = -.46, p < .001) and family deployment support (β = .05, p < .001) were associated with significantly lower loneliness. While serious life events in childhood, warzone trauma, and social support were associated with posttraumatic outcomes at T1 and T2 (ps < .01), loneliness on deployment was only associated with mental health outcomes at T1 (ps < .01) and not significantly associated with anxiety, depression, PTSD, or posttraumatic growth measured at T2 (all ps > .16). These findings enhance our understanding of loneliness in wartime and highlight the need for further work examining social buffers against posttraumatic outcomes in military veterans, particularly those who have experienced childhood trauma.