finding that 25-60% of veterans with a psychiatric disorder had been abused (Bremner et al. 1993; Engel et al. 1993; Lapp et al. 2005).

Psychiatric History

Having been diagnosed previously with a psychiatric disorder increases the likelihood of PTSD after exposure to a traumatic event. People with a history of a psychiatric disorder may have an increased likelihood of engaging in risky behavior which increases the likelihood of their exposure to traumatic events and their potential for PTSD or other stress-related disorders. Someone with a pre-existing psychiatric disorder who is exposed to wartime trauma may respond ineffectively to the traumatic event because of pre-existing symptoms, inadequate coping styles, low social support, and poor self-esteem, all of which increase the likelihood of PTSD or related disorders.

A study of Gulf War veterans by Black et al. (2004) found that the greatest risk of postwar anxiety disorder resulted from the presence of pre-existing anxiety disorders of any kind (OR 10.4, 95% CI 2.9-37.0), and pre-existing depressive disorders (OR 4.1, 95% CI 1.9-8.9). The overall likelihood of postwar anxiety disorders was increased by a factor of 4 (range, 2.2-8.9) by a previous history of any psychiatric disorder. A study of Australian Gulf War veterans by Ikin et al. (2004) found that similar percentages of Gulf War-deployed veterans (31%) and a comparison group of era veterans (33.7%) reported having had a psychiatric disorder before deployment. Most frequently, the pre-existing disorders were substance-use disorders (25-28%) and anxiety disorders (6-8%).

Hoge et al. (2004) screened 2530 U.S. infantry soldiers for mental health disorders before their deployment to Iraq in 2003. They found that 14.3% reported a moderate or severe mental health problem, 5.3% met the patient health questionnaire definition of depression, 6.4% met the definition of anxiety, 5.0% met the definition for PTSD, 17.3% reported using more alcohol than they meant to, and 12.5% had felt they wanted to cut down on their drinking. Those findings highlights that a substantial portion of military personnel may enter combat at increased risk for a psychiatric disorder on the basis of psychiatric history alone.

Hardiness, Coping Strategies, and Sense of Control

The occurrence and severity of stress-related health effects are not solely the result of interaction of physiologic processes with a threatening environment. Studies of Vietnam and Gulf War veterans indicate that particular personality or psychologic characteristics can affect a person’s reactions to deployment-related stress. Personality includes inherent tendencies toward optimism or pessimism, coping styles, resilience, and hardiness that would be expected to affect one’s ability to manage stressful events. Those characteristics are determined or modulated by the action of life experiences on genetic makeup.

One personality trait, hardiness, has been defined as a combination of commitment (feeling deeply involved in life activities), feeling in control of one’s experiences, and maintaining a sense of challenge (a positive anticipation of change). Dolan and Adler (2006) adapted the definition of hardiness in a military population to mean the degree to which military personnel are committed to and feel a sense of control over their work experiences. They surveyed U.S. Army soldiers during and after a 6-month peacekeeping mission in Kosovo. Military hardiness was correlated with psychologic but not physical health during and after deployment. Among soldiers who experienced high levels of deployment stressors, those with



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