Abstract
BACKGROUND: Military service is historically a male-dominated occupation, as such, the majority of research examining the development of mental disorder in Australian Defence Force members has had primarily male samples. While there have been mixed findings internationally regarding sex differences in rates of mental disorder and subthreshold symptoms among military personnel, across studies, the evidence tends to suggest that female military members are at least as likely as males to experience subthreshold mental health symptoms and have similar or higher rates of posttraumatic stress disorder despite the differences in roles during service. What is less understood is the impact of sex differences in symptom emergence over time and in predictors of clinical disorder. METHOD: The sample included a longitudinal cohort of Australian Defence Force members (N = 8497) surveyed at Time 1 (2010) and followed up at Time 2 (2015) on measures of anger, self-perceived resilience, trauma exposure, deployment exposure, suicidality, help-seeking, relationship satisfaction and mental health disorder symptoms. Outcomes included Subthreshold Disorder (above the optimal screening cut-off on the 10-item Kessler distress scale or posttraumatic stress disorder checklist) and Probable Disorder (above the epidemiological cut-off on the 10-item Kessler distress scale or posttraumatic stress disorder checklist). RESULTS: Results found that while lifetime trauma exposure remained the strongest predictor of later probable disorder emergence among both males and females, for females specifically, self-reported resilience was also a significant protective factor. In contrast, being in a significant relationship at Time 1 was a protective factor against the development of subthreshold disorder in males. CONCLUSION: For the first time, sex differences in mental health symptom emergence over time have been explored in a large Australian cohort of military members. The capacity to adapt and bounce back after adversity emerged as a proactive factor against poor mental health for females in the military and could be addressed as part of routine skills training. Social support from significant relationship was particularly important for males' mental health, suggesting that maintaining positive relationships and supporting military spouses and partners are critical for males' mental health.