Studies in the general population

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1 VIOLENCE AND TRAUMA Childhood adversity and traumatic exposures during deployment as predictors of mental health in Australian military veterans Wu Yi Zheng, 1 Jeeva Kanesarajah, 2 Michael Waller, 2 Annabel C. McGuire, 2 Susan A. Treloar, 2 Annette J. Dobson 2 Studies in the general population suggest that individuals who report high levels of childhood adversity are at higher risk of health problems in later life, including personality disorders, 1 alcoholism, 2,3 drug abuse, 3 depression, 2,3 suicide attempts 3 and severe obesity. 3 In the military context, childhood adversity has consistently been identified as a pre-enlistment risk factor associated with symptoms of post-traumatic stress disorder (PTSD), 4-6 depression, 4,5 anxiety, 5,7 risky driving behaviour, 8 alcohol misuse, 9,10 and self-harm, suicidal ideation and behaviour. 11 A number of authors have inferred from these results that prior traumas, such as childhood adversity, can increase individuals vulnerability to mental health problems when faced with traumatic events, such as combat exposure, in adult life. 9,12 However, in the few studies that have specifically considered whether childhood adversity modifies the effect between traumatic exposure on deployment and mental health problems, the results have been mixed. Cabrera et al. found traumatic exposure had a greater effect on the mental health of individuals with no history of childhood adversity compared to those who had experienced a high level of childhood adversity. 4 These authors suggested that exposure to childhood adversity may have some protective effect that improves the ability to cope with traumatic stress. Similar results were also found with a sample of Persian Gulf War veterans. 13 However, other research which assessed PTSD, 5,6 anxiety, 7 and depression and alcohol use 5 found Abstract Objective: To examine whether the relationship between traumatic exposure on deployment and poor mental health varies by the reported level of childhood adversity experienced in Australian military veterans deployed to the Bougainville or East Timor military operations. Methods: Cross-sectional self-reported survey data were collected in 2008 from 3,564 Australian military veterans who deployed to East Timor or Bougainville on their deployment experiences, health and recall of childhood events. Multivariable logistic regression was used to investigate the association between childhood adversity, deployment exposures and mental health. Results: The most common childhood adversity reported was not having a special teacher, youth worker or family friend who looked out for them while growing up. On average, responders reported experiencing 3.5 adverse childhood experiences (SD 2.7) and averaged 5.3 (SD 4.9) traumatic exposures on deployment. Both childhood adversity and traumatic exposures on deployment were associated with higher odds of poorer mental health. However, there was no evidence that level of childhood adversity modified the association between traumatic exposure and mental health. Conclusions/Implications: These findings suggest that military personnel who recalled a higher level of childhood adversity may need to be monitored for poor mental health and, if required, provided with appropriate support. Key words: childhood adversity, PTSD symptoms, alcohol dependency, depression, military no interactive effects between childhood adversity and traumatic exposure. These varied findings and interpretations demonstrate that there is still considerable uncertainty in the understanding of how childhood adversity may affect a military member s ability to deal with traumatic exposures on deployment. In an era in which military personnel have been increasingly deployed on overseas operations, it is important that risk factors for subsequent poor mental health are identified to inform preventative and treatment strategies. We aimed to investigate the association between reported childhood adversity, traumatic exposures on deployment and mental health of Australian Defence Force (ADF) members. We investigated whether the relationship between traumatic exposure on deployment and poor mental health (PTSD symptoms, psychological distress, and alcohol dependency) varies by the reported level of childhood adversity experienced. Data from studies of two deployments of ADF members (Bougainville and East Timor, now Timor-Leste) are used to address these aims. 1. Australian Institute of Health Innovation, Macquarie University, New South Wales 2. School of Public Health, The University of Queensland Correspondence to: Ms Jeeva Kanesarajah, School of Public Health, The University of Queensland, Herston Campus, Brisbane, QLD 4006; j.kanesarajah@uq.edu.au Submitted: April 2015; Revision requested: June 2015; Accepted: October 2015 The authors have stated they have no conflict of interest. Aust NZ J Public Health. 2016; 40:10-15; doi: / Australian and New Zealand Journal of Public Health 2016 vol. 40 no. 1

2 Violence and Trauma Childhood adversity in Australian veterans Method Study design and participants Retrospective data from the Bougainville (deployments between 1997 and 2003) and East Timor Deployment Health Studies (deployments between 1999 and 2005) were collected in These studies involved self-report cross-sectional surveys, each with a deployed group and a comparison group who did not deploy. Participation was voluntary and informed consent was obtained prior to participation. Retrospective information on the ADF members physical and mental health symptoms and experiences of childhood adversity was collected in each survey. In addition, participants in the deployed group were surveyed on their deployment experiences. Figure 1: Study sample flow chart. Bougainville Deployment Health Study deployed group Bougainville veterans eligible to participate N = 4,775 Responded n = 2,342 Responders in research sample n = 3,954 Responded to at least one childhood adversity question n = 3,678 Responder assigned a childhood adversity level n = 3,564 In the Bougainville study, all 4,775 ADF members who had deployed to Bougainville were eligible to participate (Figure 1). In contrast, for the East Timor study, a stratified random sampling design was used to select, from a nominal roll of 19,710, a sample of 3,999 East Timor veterans. The sample was selected to be representative of the nominal roll based on Service (Navy, Army, Air Force), service type (active regular or reserve), age group and gender. The response rates for the deployed group in each study were 49% (n=2,342/4,775) and 46% (n=1,833/3,999), respectively. A full description of data collection procedures is provided elsewhere. 14,15 This research included only those who had deployed to either Bougainville or East Timor (n=3,954). If a responder had completed East Timor Deployment Health Study deployed group East Timor veterans selected to participate N = 3,999/19,710 Responded n = 1,833 Responded to East Timor and Bougainville deployment surveys n = 221 Only East Timor survey responses used in analysis both the Bougainville and East Timor surveys (n=221), responses from the East Timor deployment were used for these analyses, as the East Timor deployment was generally more warlike and the experiences were more recent. Ethical approval for this research was obtained from the Australian Department of Defence Joint Health Command Low Risk Ethical Review Panel and The University of Queensland Behavioral and Social Sciences Ethical Review Committee. Measuring childhood adversity Childhood adversity was measured by the 16 true/false items developed by the King s Centre for Military Health Research, King s College London, UK, for their studies on UK military personnel. 9,16 Three of the 16 items were adapted from the Adverse Childhood Experiences (ACE) study, 3 while the remaining items were based on evidence on the impact of childhood exposures on subsequent health outcomes in adolescents and young adults, which is described elsewhere. 16 There were six items measuring quality of the childhood family environment, four items measuring externalising behaviour, three items measuring physical/psychological violence events and three items measuring relationships with other adults. The childhood adversity score was created by summing responses to these items. Scores were then divided into tertiles: 0 to 2 experiences were classified as no or low childhood adversity, 3 or 4 experiences as moderate level, and 5 to 16 experiences as high childhood adversity. This ensured there were sufficient responders in each childhood adversity level for the analysis that compared between them. A total of 3,678/3,954 responders completed at least one childhood adversity question. Of the 3,678 responders, 3,564 participants provided sufficient responses to calculate a childhood adversity score and were assigned a childhood adversity level. A full list of items in the scale is shown in Table 1. Measuring traumatic experiences on deployment To measure traumatic exposures on deployment to Bougainville or East Timor, the 12-item Traumatic Stress Exposures Scale-Revised (TSES-R2) was used. 17 The TSES-R2 is designed to measure frequency and severity of traumatic events. As part of this scale, participants were asked how 2016 vol. 40 no. 1 Australian and New Zealand Journal of Public Health 11

3 Zheng et al. Article often they experienced each of the 12 events while on deployment to Bougainville or East Timor (subscale TSES-R2-A). The items include handling or seeing dead bodies; being in danger of being killed; witnessing human degradation and misery; and fearing potential exposure to contagious disease, toxic agent or injury on deployment. Responses were measured on a 5-point scale (0 never to 4 very often [11 or more times] ). The total traumatic exposure score was created by summing responses to these scale items. In the analysis, traumatic exposure score is treated as a continuous variable, where a one-unit increase in traumatic exposure score means experiencing one extra exposure on deployment, or experiencing a particular exposure slightly more frequently. Table 1: Frequency of each childhood adversity item for the Bougainville/East Timor deployment group. Childhood Adversity Experienced N n % No special teacher/youth worker/family friend who looked out for them 3,646 3, Did things that should have or did get them in trouble with the police 3,645 1, No member of family to talk to about things important to them 3,657 1, Did not come from a close family 3,668 1, Used to get shouted at a lot at home 3, Regularly used to see physical fighting or verbal abuse between parents 3, At least one parent had problems with alcohol or drugs 3, Family did not do things together 3, Did not feel valued by family 3, No special thing /activity which made them feel special/proud 3, Often was in physical fights at school 3, Was suspended or expelled from school 3, Often used to play truant from school 3, Had problems with reading and writing at school and needed extra help 3, Regularly hit or hurt by a parent or caregiver 3, Spent time in local authority care or social services 3, Post-deployment mental health Post-Traumatic Stress Disorder (PTSD) symptoms were measured using the PTSD Check List Civilian (PCL-C). This 17-item self-administered questionnaire has excellent test retest reliability and very high internal consistency. 18 Total scores range from 17 to 85. A variety of cut-off scores have previously been used as indicators of clinical levels of PTSD symptoms in military populations. 19,20 We chose a cut-off of 30 in order to capture those with sub-syndromal symptoms of PTSD. The Kessler 10 (K10) instrument was used to assess psychological distress. 21 The K10 is a validated general measure of psychological distress with scores providing a measure of risk of mental health problems. Total scores were created by summing the item responses (range from 0 to 50) and a cut-off of 20 was used to screen for at least mild mental disorder. 22 Alcohol dependency was assessed using the Alcohol Use Disorders Identification Test (AUDIT), which quantifies current alcohol use and screens for alcohol use disorders. 23,24 The scale was developed for the identification of currently active, hazardous and harmful alcohol consumption. Total scores range from 0 to 40 and a cut-off score of 16, which represents high levels of alcohol problems, was used. 23 Statistical analysis Analysis was performed using the statistical software package SAS version The estimated means reported were calculated for those who responded to all items in each measure of interest. In categorical data analysis, if someone did not complete all items in a scale but it was possible to definitively determine their category based on their responses, the person was assigned to that category. To determine potential confounders, associations between demographic, deployment characteristics and childhood adversity were investigated using chi-square tests. Multivariable binary logistic regression models were used to quantify associations between traumatic exposures (TSES-R2-A scale), the level of childhood adversity, and dichotomised mental health outcomes. The traumatic exposure variable was included as a linear and a quadratic term in a logistic regression model to assess the linearity of its association with mental health outcomes; there was no statistical evidence of a nonlinear relationship. The statistical interaction between childhood adversity level and traumatic exposure and its association with poorer mental health was modelled. The likelihood ratio test was used to assess the statistical significance of childhood adversity as an effect modifier. Sensitivity analyses were performed using multivariable linear regression to quantify the association between continuous variables traumatic exposure, childhood adversity score and mental health score as well as to investigate the interaction effect between childhood adversity score and traumatic exposure on mental health. All multivariable regression analysis were adjusted for the potential confounding effects of age ( 34, 35-44, 45-54, 55 years), sex, service (Navy, Army or Air Force), service status (active regular, reserve, ex-serving) and rank (officer or enlisted). Results A total of 3,678 ADF members who had deployed to Bougainville or East Timor responded to the health studies and completed at least one question on childhood adversity. Table 1 showed that 86.3% (n = 3,146/3,646) of responders did not have a special teacher, youth worker or family friend who looked out for them while growing up. The next most common adversities were, not having any family member they could talk to about things that were important to them and did things that should or did get them into trouble with the police (Table 1). On average, responders were 41 years old (SD 8.1) when surveyed, reported experiencing 3.5 adverse childhood experiences (SD 2.7) and averaged 5.3 (SD 4.9) traumatic exposures on deployment. Among the responders, 27.6% (n=966/3,506) scored higher than 30 on the PCL-C; 25.4% screened for at least mild mental disorder (K10 20: n=903/3,553); while 7.5% had a high level of alcohol problems (AUDIT 16: n=267/3,542). Overall, 29.5% of responders reported a high level of childhood adversity (endorsing five or more items), with male responders, responders aged years of age, or enlisted members reporting significantly more adversity (Table 2). When childhood adversity and traumatic exposure on deployment were mutually adjusted for, responders who had more exposure to traumatic events on deployment and those who reported greater childhood adversity were more likely to report symptoms of PTSD, at least mild mental 12 Australian and New Zealand Journal of Public Health 2016 vol. 40 no. 1

4 Violence and Trauma Childhood adversity in Australian veterans disorder and high levels of alcohol problems (Table 3). For each level of childhood adversity, respondents with higher scores of traumatic exposure were significantly more likely to report symptoms of PTSD, at least mild mental disorder and high level of alcohol problems (Table 4). However, the strength of association between traumatic exposure and each mental health measure was similar among those who experienced no or low, moderate or high childhood adversity. Overall, there was no evidence that the experienced level of childhood adversity modified the association between traumatic exposure and poor mental health (PTSD symptoms: chi-squared = 4.4, df = 2, p = 0.11; at least mild mental disorder: chi-squared = 5.7, df = 2, p =0.06; high level of alcohol problems: chi-squared = 2.9, df = 2, p =0.23). Table 2: Childhood Adversity by ADF member s demographic and service characteristics (N=3,564). Childhood Adversity, n (row %)* No or Low (0 2) Moderate (3/4) High ( 5) Overall 1,602 (44.9) 911 (25.6) 1,051 (29.5) Sex Male Female Age group (years) Service Navy Army Air Force Serving Status Active Regular Reserve Ex-serving Rank Officer Enlisted 1,330 (42.6) 272 (60.7) 386 (46.9) 732 (44.9) 361 (41.9) 123 (49.2) 320 (45.7) 1,144 (43.9) 138 (53.3) 890 (45.2) 531 (46.5) 181 (40.1) 625 (57.1) 977 (39.6) * Numbers might not add up to totals because of missing data. 819 (26.3) 92 (20.6) 232 (28.3) 405 (24.8) 217 (25.2) 57 (22.8) 178 (25.4) 678 (26.0) 55 (21.2) 528 (26.8) 265 (23.2) 118 (26.2) 225 (20.6) 686 (27.8) 969 (31.1) 82 (18.4) 202 (24.6) 495 (30.3) 284 (33.0) 70 (28.0) 202 (28.9) 783 (30.1) 66 (25.5) 553 (28.1) 346 (30.3) 152 (33.7) 245 (22.4) 806 (32.6) P- value < <0.001 Table 3: Associations of childhood adversity and traumatic exposure score with poor mental health measures in ADF members. Childhood Adversity No or Low (0-2) Moderate (3/4) High (5+) PTSD Symptoms PCL-C 30 At Least Mild Mental Disorder K10 20 High Level of Alcohol Problems AUDIT 16 n (%) aor (95% CI)* n (%) aor (95% CI)* n (%) aor (95% CI)* 263 (21.3) 191 (27.6) 310 (38.3) 1.00 (baseline) 1.36 (1.08, 1.71) 2.06 (1.67, 2.55) Sensitivity analysis results The findings did not change appreciably when the analyses were repeated using linear regression. In these analyses, total childhood adversity score and mental health scores, in addition to traumatic exposure score, were fitted in the model as continuous variables instead of their categorical versions. On average, responders who experienced greater childhood adversity or traumatic exposure scored higher on the PCL-C, K10 and AUDIT scales after adjusting for other potential confounders (see Supplementary Table 1, available with the online version of this article). However, there was no evidence of an interaction effect between childhood adversity score and traumatic exposure score on mental health scores (see Supplementary Table 2, available online). 215 (17.3) 204 (29.1) 297 (35.8) 1.00 (baseline) 1.91 (1.52, 2.40) 2.42 (1.95, 3.00) 65 (5.2) 57 (8.2) 92 (11.0) 1.00 (baseline) 1.44 (0.98, 2.09) 1.88 (1.33, 2.64) Traumatic Exposure Score 1.14 (1.12, 1.16) 1.10 (1.08, 1.12) 1.09 (1.06, 1.11) aor, adjusted odds ratio; 95% CI, 95% Confidence Interval. * Binary logistic regression models include both childhood adversity and traumatic exposure score variables and are adjusted for age group ( 34, 35-44, 45-54, 55), sex, service (Navy, Army and Air Force), service status (active regular, reserve, ex-serving) and rank (officer and enlisted). Discussion Analyses in this paper showed that childhood adversity and traumatic exposures on deployment were both strongly associated with poorer mental health outcomes in Australian veterans. Those who reported higher levels of childhood adversity were likely to have higher odds of poor mental health. These finding were consistent across the three mental health measures examined (PTSD symptoms, psychological distress and alcohol problems). In the interpretation of these results, it is important to acknowledge that some veterans may have had to recall deployment experiences up to 21 years after their deployment to Bougainville or East Timor, as well as their perceptions on childhood experiences. Further, this recall could have been affected by their mood while completing the survey, as well as any ongoing mental health issues. Despite these limitations, our findings seem to be consistent with previous research and suggest that higher levels of childhood adversity place an individual at a greater risk for developing symptoms of post-traumatic stress, 4,5,9,12,26 high psychological distress, 5,7 and alcohol misuse 2,3,9 in later life. Although data on severe childhood adversity events such as sexual abuse were not collected in the current study, our results indicated that childhood adversity measured with less severe events such as getting shouted at or not being from a close family were associated with worse mental health. There is good evidence from previous research to suggest that the quality of family environment while growing up is important for later health These findings provide further support to the hypothesis that perceived childhood adversity is associated with mental health problems in adulthood. 2,3 The finding that traumatic exposures on military deployments are associated with poor mental health in deployed personnel 3,4,13,26 has been well established. However, there have been contrasting hypotheses as to whether those with childhood adversity are at increased 5,12,30 or decreased 4,13 risk of mental health problems after experiencing traumatic exposures on deployment. Some have proposed that prior childhood adversity might increase vulnerability to stressful events in adulthood. 31 Life stressors, such as childhood adversity, may increase 2016 vol. 40 no. 1 Australian and New Zealand Journal of Public Health 13

5 Zheng et al. Article Table 4: The association between one unit increase in traumatic exposure score and poor mental health, at no or low, moderate or high levels of childhood adversity- results from the logistic regression interaction model. PTSD Symptoms PCL-C 30 aor (95% CI) vulnerability by reducing one s ability to cope with subsequent events. 32 Another perspective is that childhood adversity has an inoculating effect 5,13 that may improve veterans abilities to handle traumatic events. It may be that negative life experiences early on allowed these individuals to adopt and fine-tune coping strategies to deal with adversity later on in life. 33 Alternatively, military members exposed to childhood adversity may exhibit lower reactivity to traumatic experiences on deployment because of increased familiarity with stressful events and better methods to adapt in these situations. 4,32 Our results demonstrated that there was little difference in the effect of traumatic exposures on mental health in those with low, moderate or high levels of childhood adversity. This finding differs from results of previous studies suggesting that those who were exposed to high levels of childhood adversity were somewhat protected against the effects of traumatic exposures on deployment, 4,13 as well as research that suggest prior childhood vulnerability may increase vulnerability to stressful events as an adult. 31,32 We found no such interactions or effect modification. Study strengths, limitations and future directions Data from a large cohort of current and ex-serving ADF members deployed on contemporary overseas deployments were used in this research. Hence, these findings may be generalisable to other contemporary military populations. However, the crosssectional nature of these data does not allow any firm conclusions to be made on causal relationships. Recall bias may have influenced reports on childhood adversity and traumatic experiences on deployment. While this study specifically focused on deployments to Bougainville and East Timor, the experiences At Least Mild Mental Disorder K10 20 aor (95% CI) High Level of Alcohol Problems AUDIT 16 aor (95% CI) Childhood Adversity No or Low (0 2) Moderate (3/4) High ( 5) 1.15 ( ) 1.15 ( ) 1.11 ( ) 1.11 ( ) 1.12 ( ) 1.07 ( ) 1.12 ( ) 1.07 ( ) 1.07 ( ) aor, adjusted odds ratio; 95% CI, 95% Confidence Interval. * Binary logistic regression models include childhood adversity (a three level categorical variable), traumatic exposure score (a continuous variable), and the interaction between these two variables and are adjusted for age group( 34, 35-44, 45-54, 55 years), sex, service (Navy, Army and Air Force), service status(active regular, reserve, ex-serving) and rank (officer and enlisted) resulting from previous deployments to other areas may have knowingly or unknowingly influenced the participant responses in this study. Respondents may have also selectively suppressed reporting information that they deemed too sensitive or revealing and that could have consequences for their military career. Even though the health outcomes used in this study were measured using standard, well-validated scales, the selfreported nature of the data meant that the health outcomes represented symptoms rather than clinical diagnosis. Future research is needed that uses data from a longitudinal study that measures mental health, traumatic exposures, childhood adversity and other life events at the time of enlistment, before deployment and postdeployment. Such data would be required to establish possible causal relations between traumatic exposures on deployment and subsequent mental health problems, as well as to assess the role of childhood adversity in the aetiology of mental health. In our current analysis, we have used the same scoring as described by Iversen and colleagues, 9 assuming that the severity of each childhood event is equal. However, some childhood events may have a greater impact on mental health compared to others. The use of a scale that included weights for severity of adverse events would be preferable for future studies. Implication of results Understandably, much of the focus of deployment health studies has been on the consequences of traumatic experiences on deployment: traumatic exposures on deployment were also strongly associated with poorer mental health in this study. However, when assessing the mental health of military members, it is also important to consider other traumatic experiences that have occurred over the lifetime of the individual, such as childhood vulnerabilities, civilian stressors and previous deployments. 34 A broader range of information should be considered in order to understand the mental health of military personnel and more clearly identify those who may be at risk or who may require treatment. Consequently, the most important finding from this paper is that ADF members with a history of childhood adversity are at a higher risk of developing symptoms of PTSD, psychological distress and alcohol misuse. Techniques aimed at addressing adverse childhood experiences may improve their health and psychological resilience. 35 It is unclear whether additional support for those who have experienced childhood adversity, such as resilience training, 36 would provide protection from adverse outcomes of traumatic exposures later in life. Conclusion This is the first study to investigate the association between childhood adversity and post-deployment mental health in a sample of Australian Defence Force members. Results suggest that high childhood adversity is associated with mental health problems in adulthood. However, in this cohort of Australian military veterans, prior childhood adversity had little effect on the association between traumatic exposures and mental health vulnerability. From a policy perspective, the established link between childhood adversity and mental health vulnerability suggests that such individuals may need to be monitored, as they may be at higher risk of developing mental health problems. Acknowledgement We thank the Australian Defence Force members who participated in the surveys and the Australian Department of Defence for funding the Bougainville and East Timor Deployment Health Studies and facilitating the data collection. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or representing the views of the Australian Defence Force or Department of Defence. Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. 14 Australian and New Zealand Journal of Public Health 2016 vol. 40 no. 1

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Prof Psychol Res Pr. 1993;24(1): Cohn A, Hodson S, Crane M. Resilience training in the Australian Defence Force. In Psych Bull April. Supporting Information Additional supporting information may be found in the online version of this article: Supplementary Table 1: Associations between childhood adversity, traumatic exposures scores and mental health measure total scores vol. 40 no. 1 Australian and New Zealand Journal of Public Health 15