Increased Incidence Rate of Trauma- and Stressor-related Disorders in Denmark After the Breivik Attacks in Norway

Epidemiology. 2017 Nov;28(6):906-909. doi: 10.1097/EDE.0000000000000705.


Background: On 22 July 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 geographic proximity-would 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 change in the incidence of trauma- and stressor-related disorders after the Breivik attacks.

Results: The incidence rate increased by 16% over the following 1½ years after the Breivik attacks, corresponding to 2736 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 geographic proximity and media coverage may exacerbate effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Denmark / epidemiology
  • Humans
  • Incidence
  • Norway
  • Psychological Trauma / epidemiology*
  • Psychological Trauma / psychology
  • Registries*
  • September 11 Terrorist Attacks / psychology
  • Stress Disorders, Post-Traumatic / epidemiology*
  • Stress Disorders, Post-Traumatic / psychology
  • Stress, Psychological / epidemiology*
  • Stress, Psychological / psychology
  • Terrorism / psychology*
  • United States