9/11: Impact on mental illness far beyond U.S. borders

This is the conclusion of a recent population-wide study from Denmark, which demonstrates a "significant and immediate" spike in the diagnoses of trauma and stressor related disorders (e.g. adjustment disorders or post-traumatic stress disorder) in Denmark in the weeks and months after the traumatic events of September 11, 2001, even though the Nordic country was not directly impacted by the attacks.

The study, which was financed by the Carlsberg Foundation, was carried out by political scientists and medical researchers from Aarhus University, University of Copenhagen and Stanford University. It has just been published online ahead of print in the American Journal of Epidemiology.

In the article, the authors argue that their finding "sadly confirms that one of the alleged purposes of (certain types of) terrorism -- to generate mass-scale attention and intimidation -- is in fact achieved."

Specifically, the Danish study documents a 16 percent increase in trauma and stressor related disorders recorded by psychiatric services in the week right after the September 11 attacks. Remarkably, the effect persisted for an extended period after the initial shock, and half a year after the 9/11 attacks, the incidence of trauma and stressor related disorders remained elevated about 5 percent above the normal level. It did not return to normal until about a year after the attacks.

In the article, the authors also speculate about the role of mass media in generating the observed effect: "The extra-national character of the post-9/11 deterioration of mental health observed in this study also highlights the pronounced importance of mass media in transmitting stress-inducing information to populations in countries far removed from the target of the attack."

Based on this observation, the authors argue that the effect of more recent and future terrorist attacks could be even stronger given the highly visual and real-time nature of today's internet-based mass media.