Mental health consequences of overstretch in the UK armed forces: first phase of a cohort study.

OBJECTIVE To assess the relation between frequency and duration of deployment of UK armed forces personnel on mental health. DESIGN First phase of a cohort study. SETTING UK armed forces personnel. PARTICIPANTS Operational history in past three years of a randomly chosen stratified sample of 5547 regulars with experience of deployment. MAIN OUTCOME MEASURES Psychological distress (general health questionnaire-12), caseness for post-traumatic stress disorder, physical symptoms, and alcohol use (alcohol use disorders identification test). RESULTS Personnel who were deployed for 13 months or more in the past three years were more likely to fulfil the criteria for post-traumatic stress disorder (odds ratio 1.55, 95% confidence interval 1.07 to 2.32), show caseness on the general health questionnaire (1.35, 1.10 to 1.63), and have multiple physical symptoms (1.49, 1.19 to 1.87). A significant association was found between duration of deployment and severe alcohol problems. Exposure to combat partly accounted for these associations. The associations between number of deployments in the past three years and mental disorders were less consistent than those related to duration of deployment. Post-traumatic stress disorder was also associated with a mismatch between expectations about the duration of deployment and the reality. CONCLUSIONS A clear and explicit policy on the duration of each deployment of armed forces personnel may reduce the risk of post-traumatic stress disorder. An association was found between deployment for more than a year in the past three years and mental health that might be explained by exposure to combat.