Although much is known about psychopathology such as post-traumatic stress disorder (PTSD) and depression following bushfire (also known as wildfire), little is known about prevalence, trajectory and impacts for those experiencing general adjustment difficulties following exposure to these now-common events.

This was an exploratory analysis of a large cohort study that examined the prevalence, trajectory and risk factors of probable adjustment disorder over a 10-year period following bushfire exposure.

The Beyond Bushfires study assessed individuals exposed to a large and deadly bushfire across three time points spanning 10 years. Self-report survey data from participants from areas with moderate and high levels of fire-affectedness were analysed: n = 802 participants at Wave 1 (3–4 years post-fires), n = 596 at Wave 2 (5 years post-fires) and n = 436 at Wave 3 (10 years post-fires). Surveys indexed fire-related experiences and post-fire stressors, and comprised the six-item Kessler Psychological Distress Scale (probable adjustment disorder index), four-item Posttraumatic Stress Disorder Checklist (probable fire-related PTSD) and nine-item Patient Health Questionnaire (probable major depressive episode).

Prevalence of probable adjustment disorder was 16% (Wave 1), 15% (Wave 2) and 19% (Wave 3). Probable adjustment disorder at 3–4 years post-fires predicted a five-fold increase in risk for escalating to severe psychiatric disorder (i.e. probable fire-related PTSD/major depressive episode) at 10 years post-fires, and was associated with post-fire income and relationship stressors.

Adjustment difficulties are prevalent post-disaster, many of which are maintained and exacerbated over time, resulting in increased risk for later disorder and adaptation difficulties. Psychosocial interventions supporting survivors with adjustment difficulties may prevent progression to more severe disorder.

The mental health impact of the initial years of military service is an under-researched area. This study is the first to explore mental health trajectories and associated predictors in military members across the first 3–4 years of their career to provide evidence to inform early interventions.

This prospective cohort study surveyed Australian Defence personnel (n = 5329) at four time-points across their early military career. Core outcomes were psychological distress (K10+) and posttraumatic stress symptoms [four-item PTSD Checklist (PCL-4)] with intra-individual, organizational and event-related trajectory predictors. Latent class growth analyses (LCGAs) identified subgroups within the sample that followed similar longitudinal trajectories for these outcomes, while conditional LCGAs examined the variables that influenced patterns of mental health.

Three clear trajectories emerged for psychological distress: resilient (84.0%), worsening (9.6%) and recovery (6.5%). Four trajectories emerged for post-traumatic stress, including resilient (82.5%), recovery (9.6%), worsening (5.8%) and chronic subthreshold (2.3%) trajectories. Across both outcomes, prior trauma exposure alongside modifiable factors, such as maladaptive coping styles, and increased anger and sleep difficulties were associated with the worsening and chronic subthreshold trajectories, whilst members in the resilient trajectories were more likely to be male, report increased social support from family/friends and Australian Defence Force (ADF) sources, and use adaptive coping styles.

The emergence of symptoms of mental health problems occurs early in the military lifecycle for a significant proportion of individuals. Modifiable factors associated with wellbeing identified in this study are ideal targets for intervention, and should be embedded and consolidated throughout the military career.