A full 15% of survivors tested positive for PTSD in the 2-3 years following 9/11.
"PTSD risk was greater among survivors who experienced serious life threat as defined by location in the towers, time of evacuation initiation, or dust cloud exposures," said the study's first author, Laura DiGrande, in a prepared release. "As one would expect, individuals who were exposed to several of the most troubling and life-threatening events during the disaster were at the greatest risk of PTSD."
The study found a few interesting statistics: lower-income survivors were more likely to develop PTSD, as were blacks and Hispanics. People whose employers were killed also seemed to develop PTSD at a greater rate.
Meanwhile, exactly what each of these survivors encountered seemed to affect their changes of developing PTSD. Some where injured, some saw "horror," others were caught in the dust cloud, some were on very high floors of the Twin Towers. Those who experienced more than one of these situations had significantly greater levels of PTSD, to the point where the authors could even come up with a mathematical formula for the risk of PTSD based on the number of factors the individuals encountered.
The study appears in the online edition of the American Journal of Epidemiology. The full paper is behind a subscription firewall, but you can read the abstract here.
