BACKGROUND On July 22, 2011, Anders Breivik killed 77 adults and children in Norway. Having recently documented increases in the incidence of trauma-and stressor-related disorders in Denmark after the 9/11 attacks, we hypothesized that the Breivik attacks-due to their geographical proximitywould be followed by even larger increases in Denmark. METHODS Using population-based data from the Danish Psychiatric Central Research Register (1995-2012), we conducted an intervention analysis of the

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... in the incidence of trauma-and stressor-related disorders following the Breivik attacks. RESULTS The incidence rate increased by 16% over the following 1½ years after the Breivik attacks, corresponding to 2,736 additional cases. In comparison, 9/11 was followed by a 4% increase. We also present evidence of a subsequent surge in incidence stimulated by media attention. CONCLUSION This study bolsters previous findings on extra-national consequences of terrorism and indicates that geographical proximity and media coverage may exacerbate effects.