There is little research on the consequences of large-scale violent disasters in a community despite their unfortunate prevalence over many decades. The primary source of epidemiological data for the greater New York community in dealing with the September 11, 2001, attacks was the Oklahoma City bombing. In the latter event, 45% of directly exposed adults met criteria for a major psychiatric disorder 6 months later, including 34% with posttraumatic stress disorder (PTSD). The first survey after the World Trade Center and Pentagon attacks, conducted within one week, revealed a remarkable degree of symptomatology across the nation in both adults and children. Forty-four percent of adults reported at least 1 of 5 PTSD screening symptoms in the 3–5 days after the attacks; 35% of parents reported children who had at least one symptom, and 47% of children worried about their own or someone else's safety. Coping behaviors were consistent with a community mental health model and included turning to open discussion (98%), religion (90%), and community activities (60%) in order to cope with their reactions.

Rates of disorder were also high in a survey conducted 5–8 weeks later in Manhattan below 110th Street, with 38% saying they directly witnessed the World Trade Center attack. The current prevalence of new-onset PTSD was 7.5%, and of new-onset major depressive disorder, 9.7%. This translates into 67,000 persons with PTSD and 87,000 persons with major depression. This survey also found a significant increase in tobacco, alcohol, and marijuana use, but primarily among adults already using these substances. All surveys found strong associations between media exposure and symptomatology. The greatest need at this point in the literature is therapeutics research after such traumatic events.