title: Prior adversities predict posttraumatic stress reactions in adolescents following the Oslo Terror events 2011.
abstract: BACKGROUND
  Former studies suggest that prior exposure to adverse experiences such as violence or sexual abuse increases vulnerability to posttraumatic stress reactions in victims of subsequent trauma. However, little is known about how such a history affects responses to terror in the general adolescent population.
  
  
  OBJECTIVE
  To explore the role of prior exposure to adverse experiences as risk factors for posttraumatic stress reactions to the Oslo Terror events.
  
  
  METHODS
  We used data from 10,220 high school students in a large cross-sectional survey of adolescents in Norway that took place seven months after the Oslo Terror events. Prior exposure assessed was: direct exposure to violence, witnessing of violence, and unwanted sexual acts. We explored how these prior adversities interact with well-established risk factors such as proximity to the events, perceived life threat during the terror events, and gender.
  
  
  RESULTS
  All types of prior exposure as well as the other risk factors were associated with terror-related posttraumatic stress reactions. The effects of prior adversities were, although small, independent of adolescents' proximity to the terror events. Among prior adversities, only the effect of direct exposure to violence was moderated by perceived life threat. Exposure to prior adversities increased the risk of posttraumatic stress reactions equally for both genders, but proximity to the terror events and perceived life threat increased the risk more in females.
  
  
  CONCLUSIONS
  Terror events can have a more destabilizing impact on victims of prior adversities, independent of their level of exposure. The findings may be relevant to mental health workers and others providing post-trauma health care.
authors.affiliation: Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Health, Uni Research, Bergen, Norway ; Resource Centre on Violence, Traumatic Stress and Suicide Prevention, Haukeland University Hospital, Bergen, Norway.
authors.forename: Dag Ø
authors.initials: DØ
authors.lastname: Nordanger
authors.affiliation: Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Health, Uni Research, Bergen, Norway.
authors.forename: Kyrre
authors.initials: K
authors.lastname: Breivik
authors.affiliation: Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Health, Uni Research, Bergen, Norway.
authors.forename: Bente Storm
authors.initials: BS
authors.lastname: Haugland
authors.affiliation: Regional Office for Children, Youth and Family Affairs, Region South, Norway.
authors.forename: Stine
authors.initials: S
authors.lastname: Lehmann
authors.affiliation: Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Health, Uni Research, Bergen, Norway ; Department of Social Science, Sogn of Fjordane University College, Sogndal, Norway.
authors.forename: Magne
authors.initials: M
authors.lastname: Mæhle
authors.affiliation: Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Health, Uni Research, Bergen, Norway.
authors.forename: Hanne Cecilie
authors.initials: HC
authors.lastname: Braarud
authors.affiliation: Regional Centre for Child and Youth Mental Health and Child Welfare, Uni Health, Uni Research, Bergen, Norway.
authors.forename: Mari
authors.initials: M
authors.lastname: Hysing
keywords: adolescents; posttraumatic stress; prior trauma; terror