"Low self esteem, negative life events and lack of a support network greatly increase the likelihood of PTSD," according to a new study by the Geisinger Center for Health Research.
The study followed "2,000 adult victims of the World Trade Center disaster" for two years after the event.
Some possible therapeutic methods for treating PTSD could come out of this study: "Consistent with earlier findings, the study suggests that brief psychological interventions immediately following the event can prevent long term mental health issues. Also effective is informal support from families, friends and spiritual communities. Interestingly, extensive psychological therapy appears to delay recovery."