The Relationship Between Trauma Exposure, Somatic Symptoms, and Mental Health in Australian Defence Force Members Deployed to the Middle East Area of Operations

Abstract

There is an increase in the prevalence of physical symptoms in military veterans who have deployed to combat zones compared to those who have not been deployed. These symptoms can be distressing, disabling, and negatively impact quality of life. Current paradigms regarding the effects of traumatic deployment exposures on military personnel tend to consider non-specific physical symptoms (that are not due to injury) as simply a comorbidity of psychological disorder following trauma, rather than independent sequelae. For example, the diagnostic criteria for a condition specifically caused by traumatic exposures, posttraumatic stress disorder (PTSD), do not include physical symptoms. Uncertainty surrounding the aetiology of physical symptoms has led to some fierce controversies, such as the existence of Gulf War Syndrome. The aim of this thesis was to examine how physical and psychological symptoms occur independently as well as co-occur in veterans post-deployment, and to examine the strength of associations between traumatic deployment exposures (TDEs) and these profiles of physical and psychological symptom presentation. A further aim was to explore how well a checklist of physical symptoms could identify concurrent PTSD. The final aim was to examine whether inflammation mediated associations between TDEs and physical symptoms. Data used in this thesis were from several related studies of Australian Defence Force (ADF) members who deployed to the Middle East Area of Operations (MEAO) from 2001 to 2012. These studies were commissioned by the Australian Government’s Department of Defence to explore the impact of increased operational tempo on the health of military personnel. These large-scale correlational studies surveyed tens of thousands of personnel using self-reported questionnaires which included gold-standard measures of psychological distress and PTSD, as well as checklists of trauma exposure and physical symptoms. This thesis substantiated prior findings of high rates of comorbidity between PTSD and physical symptoms in veterans. While results confirmed that physical and psychological symptoms can co-occur, analyses identified a subgroup of veterans who exhibited physical symptoms without psychological distress; this ‘physical only’ presentation was as common as the ‘psychological only’ and comorbid symptom presentations. Moreover, this presentation was associated with lower quality of life, and as such is worthy of clinical attention. Importantly, TDEs showed similar associations with both ‘physical only’ and ‘psychological only’ symptom presentations. As with First Gulf War research, there did not appear to be a particular post-deployment physical ‘syndrome’; while symptoms often co-occurred, it was symptom number and intensity rather than type that identified affected veterans. A list of 10 physical symptoms demonstrated good diagnostic utility for predicting cases of concurrent PTSD. The findings also suggest that sub-types of PTSD exist, differentiated by the level of somatic symptoms. While a relationship was found between some individual physical symptoms and inflammation, the hypothesis that inflammation mediates the relationship between trauma and physical symptoms was not supported. These findings validate physical symptoms as a discrete symptom outcome following deployment, and this presentation had a similar prevalence to co-occurring physical and psychological symptoms. Therefore, physical symptoms should not be regarded simply as a comorbidity of an underlying psychological disorder for all veterans. As physical symptoms are just as likely to occur as psychological symptoms following TDEs and they impact quality of life, they should be assessed during post-deployment screening and considered in civilian treatment of veterans. Furthermore, the inclusion of physical symptoms in PTSD screening checklists may improve PTSD identification rates and better describe the patient experience.