Imagine sitting at your desk at work, on a Friday afternoon, just waiting for the weekend to begin. Then; a loud bang, the walls are shaking, your office windows shatter. With ears ringing, you crawl out into the corridor. The guy in the office next to yours is hurt. His shirt is covered in blood. You help him down the stairs. There’s smoke and dust everywhere. By the main entrance you pass someone who is beyond help.

Or; you are on summer holiday, relaxing at the family cottage. Suddenly, your husband calls out, telling you to come and watch the news. On the TV you see pictures from the bombed-out office building where you normally spend your workdays. You try to remember; who among your colleagues is on holiday this week? And who is at work, now possibly dead or injured? You immediately call a colleague; all she can tell you is that a bomb has gone off. No one knows what to do next.

On July 22^nd 2011, these scenarios sadly became reality when a right-wing extremist triggered a car bomb in the executive government quarters in Oslo, Norway. Several office buildings were severely damaged in the blast. Luckily, as the terror attack happened on a Friday afternoon in July, a lot of people were on holiday or had gone home for the day. Still, 8 people were killed and more than 200 were injured. The Norwegian nation was in shock.

In a new study published in Psychological Medicine, researchers at the Norwegian Centre of Violence and Traumatic Stress have examined patterns of post-traumatic stress reactions (from approx. 10 months to 3 years after the attack) in the government employees who were or were not present at work at the time of this terrible attack. What they found might hold an important key to our understanding of post-traumatic stress disorder.

For government employees who were at work that fateful day, anxiety provoking intrusive memories from the incident seem to be the main driver behind prolonged stress. Together these primary symptoms seem to work as the “psychological engine” behind the development of other common post-traumatic stress reactions, in some cases (24%), creating the complex, heterogeneous post-traumatic stress symptomatology we see in sufferers of post-traumatic stress disorder.

However, for the indirectly exposed employees (those who were on holiday or had gone home) dysphoric arousal (sleeping difficulties, irritability and problems concentrating) emerged as the best predictors of prolonged symptom severity. Although present in their symptomatology, intrusions of that fateful day do not include the same horrific details (e.g. smoke, blood, fire), and therefore do not seem to provoke the same anxious arousal. Instead a sequel of dysphoric arousal and emotional numbing, possibly related to depressive symptoms or negative affect, seem to emerge.

Why is this difference important?

This difference is important because it adds important empirical clues to contemporary theories that help us understand the development and chronicity of post-traumatic stress disorder. And in turn, it sheds light on how to treat sufferers of this debilitating disorder.

The full paper, “Towards an exposure-dependent model of post-traumatic stress: longitudinal course of post-traumatic stress symptomatology and functional impairment after the 2011 Oslo bombing” by Ø. Solberg, M. S. Birkeland, I. Blix, M. B. Hansen and T. Heir can be viewed here free of charge for a limited time