This study examined potential predictors of new-onset psychiatric disorders among Marines who deployed to combat in support of OEF/OIF. In a sample of 1113 active-duty Marines with no known previous psychiatric disorders, 18% (n
199) were diagnosed with a new-onset psychiatric disorder during the observation period. Adjusting for other variables, the strongest predictors of overall psychiatric disorders were female gender and mild TBI symptoms, while there was a strong inverse association with satisfaction with leadership.
This study’s finding that female gender was associated with an increased risk of psychiatric disorders is consistent with other military research [41
]. Goodman et al. [41
] found that female gender was an important risk factor for becoming a psychiatric casualty in a sample of U.S. soldiers deployed to Iraq. Similarly, Rundell’s investigation of U.S. military personnel engaged in OEF/OIF [9
] found a higher rate of psychiatric evacuation for women than for men. Kehle et al. [43
] and Riddle et al. [8
] found higher rates of common mental disorders (depression, anxiety, PTSD) among female than male military personnel. Civilian studies have also identified female gender as a risk factor for common mental disorders, such as anxiety and depression [44
Women who deploy to combat zones may be particularly susceptible to psychiatric disorders. These data may be a reflection of the expanding roles of female military members in the current conflicts (OEF/OIF). However, reasons for the elevated levels of mental disorders among female military members are still not well understood. While it is possible that combat exposure has a different effect on women than men, it may be that factors such as sexual harassment, sexual assault, lack of social support, marginalization, and preservice psychosocial history play a role in the gender difference [18
]. In addition, it is possible that military women have a greater propensity than their male counterparts to seek professional help for mental health problems; this is an issue that will need to be addressed in future studies. However, there is evidence that female veterans generally exhibit higher internalizing symptoms (e.g., anxiety and depression) in response to combat, whereas male veterans exhibit greater externalizing symptoms, such as substance use and antisocial behavior [8
We found that veterans who reported at least one symptom of mild TBI were at increased risk for psychiatric disorders. Although this finding is consistent with other military studies [3
], this topic deserves additional attention. Carlson and colleagues [3
] found that nearly half of the OEF/OIF war veterans screened for TBI in their sample had at least one psychiatric diagnosis, with PTSD and depression being the most common. Elevated rates of psychiatric disorders have also been found in civilians with a history of TBI [48
]. The nature of our data does not allow us to draw conclusions regarding causality with regard to mild TBI symptoms and mental disorders. Prospective, longitudinal research involving precise assessment of head injury events, TBI symptoms, psychiatric symptoms, preexisting psychiatric conditions and outcomes will be needed to determine the nature of this association.
A unique finding of this study was the association between satisfaction with leadership and mental disorders. Adjusting for other variables, service members who expressed a high level of satisfaction with leadership were about half as likely to develop a mental disorder as those who were not satisfied. This finding suggests that for military personnel who deploy to combat, good leadership may be a key protective factor against psychiatric problems. This finding is consistent with research showing that positive leadership has a beneficial effect on the mental health of combatants [4
]. To our knowledge, the present study is the first prospective military study to link leadership dissatisfaction with diagnosed mental disorders. An implication of these findings is the need for the military to continue to develop programs to improve leadership.
Consistent with previous research [6
], Marines who experienced a higher level of combat exposure, and younger Marines were at increased risk for PTSD. Also, Marines who had never been married were at reduced risk for PTSD. Marital status findings in past military research have not been consistent. Some studies have found that divorced individuals are at higher risk for PTSD [49
]; others have found minimal or no associations between marital status and PTSD [51
Similar to its inverse relationship with general mental disorders, satisfaction with leadership had a strong inverse association with anxiety disorders. Service members who expressed a high level of satisfaction with leadership were less than half as likely to develop an anxiety disorder as those who were not satisfied. Our finding that lower education was a risk factor for anxiety disorders is consistent with both military research [53
] and civilian research [55
] linking low education with PTSD and other psychiatric problems.
Results for mood disorders and adjustment disorders were similar. The key factors associated with mood disorders were female gender, number of combat deployments, and organizational commitment. The key factors associated with adjustment disorders were female gender, lower education level, and organizational commitment. Service members who expressed a high level of organizational commitment were less than half as likely to develop a mood disorder or an adjustment disorder as those with low organizational commitment. These results are consistent with research demonstrating that organizational commitment is associated with reenlistment, job satisfaction, morale, and adjustment to the military [29
]. Having a strong sense of belonging to the military organization and strongly internalized military values may help to foster psychological resilience in the face of deployment stress.
Partial support was found for the hypothesis that deployment stressors would predict overall psychiatric diagnoses. Deployment stressors had a significant univariate association with psychiatric outcomes (nonsignificant in the multivariate model), and was predictive of anxiety disorders in the multivariate model. These findings are consistent with previous research finding relationships between deployment stressors and PTSD symptom scales [5
]. To our knowledge, this is the first study to find an association between deployment stressors and diagnosed anxiety disorders.
The present study had limitations. One limitation is that our sample included only a small number of women, and these women may not be representative of the female Marine Corps population. Most of the predictor variables used in the study were based on self-report, with its associated limitations (e.g., response bias and socially desirable responding). Another limitation relates to the fact that the surveys asked for identifying information. Although confidentiality was assured, it is likely that some degree of underreporting occurred. Also, the military database from which mental disorder diagnoses were drawn did not contain information about diagnoses assigned within the theater of operations or diagnoses assigned outside the military health care system.
One other limitation of the study is that the number of psychiatric diagnoses in the sample was relatively small, making it likely that we lacked sufficient power to detect small effects. Another notable limitation relates to our use of military medical records for the mental disorder outcome data. Combat veterans in our sample who had a mental disorder but who never sought help would have been counted as not having a psychiatric diagnosis, thus adding error to the data. It is likely that this underreporting of common mental disorders (e.g., anxiety, mood disorders) would have lead to a reduction in the effect sizes found in this study, compared with true effects sizes that would have been found if all cases of mental disorders were known. In other words, the results reported in the present study are probably an underestimation of the true effect sizes.