Although the majority of the world’s population will be exposed to trauma, only a small minority will subsequently develop posttraumatic stress disorder (PTSD). Efforts to distinguish those at risk for long-term symptoms have identified several neuroanatomical and biological characteristics as well as peritraumatic responses as candidate indicators. Recent advances in analyzing molecular and genetic contributions to risk and data from prospective longitudinal cohort studies have further contributed to our evolving understanding of risk factors for the development of PTSD and longer-term outcomes. This chapter will discuss key findings from research on pre-, peri-, and posttrauma exposure biological contributions to PTSD.

Objective: There is emerging evidence that first responders, like military personnel, are at risk for exposure to potentially morally injurious events. However, studies examining expressions of moral injury in first responders are nascent, in large part due to the limited number of measures validated for use in this population. To address this gap, the present study sought to investigate the psychometric properties of the Expressions of Moral Injury Scale-Military Version (EMIS-M) in a sample of first responders. Method:The psychometric properties of the EMIS-M were investigated in a sample of 228 first responders to determine reliability, convergent validity, discriminative validity, and divergent validity. In addition, confirmatory factor analysis was conducted to test the bifactor model identified in a veteran sample (Currier et al., 2018). Results: Results yielded an excellent fit for the bifactor model with correlated self-directed and other-directed subscales identified in the EMIS-M development study. In addition, the measure evidenced strong reliability, convergent validity, discriminative validity, and divergent validity. Conclusions: The findings of the present study suggest that the Expressions of Moral Injury Scale-First Responder Version is a psychometrically sound measure capable of assessing self-and other-directed expressions of moral injury in first responders. The significance of these findings to our understanding of moral injury in first responders and their implications for future research are discussed. Clinical Impact StatementThe findings of this study contribute to the limited extant research suggesting that first responders may be impacted by moral injury. Further, this study's findings suggest that the Expressions of Moral Injury Scale-First Responder Version (EMIS-FR) is a psychometrically sound tool with which clinicians, researchers, and public safety agencies can assess symptoms related to moral injury in first responders. Since the EMIS-FR does not ask respondents to indicate the specific potentially morally injurious event that they were exposed to, this measure may have optimal utility as a minimally distressing tool for public safety agencies to assess expressions of moral injury.