Background The 2011 Great Japan tsunami and nuclear leaks displaced 300 000 people, but there are no large studies of psychological distress suffered by these refugees. Aims To provide a first assessment of major factors associated with distress and dysfunctional behaviour following the disasters. Method All refugee families living in Miyagi were sent a questionnaire 10-12 months after the disasters. 21 981 participants (73%) returned questionnaires. Questions assessed psychological distress (Kessler Psychological Distress Scale, K6), dysfunctional behaviours, demographics, event exposure, change in physical activity, household visitors and emotional support. Results Nine percent scored 13+ on the K6 indicating risk of severe mental illness. Psychological distress was greater among Fukushima refugees. Demographic variables, family loss, illness history and change in physical activity were associated with psychological distress and dysfunctional behaviours. Associations between psychological distress and dysfunction and visitors/ supporters depended on relation to supporter. Conclusions Practitioners need to recognise existing disease burden, community histories and family roles when intervening following disasters. © The Royal College of Psychiatrists 2015. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

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