"We cannot assume that everyone will have trauma reactions, Dass-Brailsford says. "We shouldn't be projecting that." Patricia Watson, of the National Center for Child Traumatic Stress at the University of California, Los Angeles, explains that labeling someone as needing help just based on their exposure also implies "that they don't have the resources to recover on their own, effectively undermining their own abilities and their chances of viewing themselves as a stronger person via having to solve their own problem."
Another reaction frequently projected on survivors of the attacks is the notion of survivor guilt. Although it is no longer recognized as a formal condition—now living, diagnostically, as a part of PTSD—it is especially common among those "who used to fight together or endure adversity together, such as firefighters, police officers or soldiers," Neria says. And for victims of 9/11, it is much more likely to play a role in overall PTSD if the affected individual survived and a close friend or colleague did not.
An uneven recovery
In general, the prevalence of PTSD tends to decline steadily in the months and years after a traumatic event, especially if people can get back to relatively normal routines. Research conducted in New York showed that the rates of PTSD among the general population eased from about 5 percent a year after the attacks to 3.8 percent two years later, according to work published in 2006 in The Journal of Nervous and Mental Disease.
Even many of the first responders and long-term cleanup workers seem to have largely recovered psychologically. But one group of workers has curiously not followed this trend: retired firefighters. In some studies, they seemed to have an increased prevalence of PTSD as time went on.
Some 22 percent of retired firefighters who responded on 9/11 were still suffering from PTSD some four and six years after the event, according to research published earlier this year in Public Health Reports.
Dass-Brailsford suggests that in addition to having to cope with the trauma of the event, having gone on disability or into early retirement "means that you're not working, you're not occupying your time, and you have more time to sit and think about what happened to you, so your reactions become stronger." Additionally, leaving behind a highly active and service-oriented job might result in a feeling that "you're not able to do anything meaningful," she says, which could add to depression and stress levels.
First responders of any type also rely on having delayed emotional reactions to best perform their stressful jobs. "They develop a capacity to contain their reactions so they can deal with it later" and get through the task at hand—whether it is rescuing people from a fire or pulling the injured from a car accident, Dass-Brailsford says.
And in the general population as well, "in the immediate aftermath of a traumatic event, a lot of people are numb," Dass-Brailsford explains. "For some people that state of shock and numbness can last a long time, sometimes for a number of years." After Katrina, for example, widespread mental health problems, such as debilitating depression and suicides, became more widespread several months after the event.
Research has also found that basic differences in socioeconomic status can make big differences in how likely someone is to have sustained PTSD. One study found that 9/11 survivors who earned less than $25,000 a year had a 49 percent chance of having PTSD, whereas those who made more than $100,000 per annum had only a 6 percent risk.
And not everyone who suffered from PTSD or other symptoms the event had any direct contact with the attacks—or even lived in the affected areas. One survey, published in 2002 in JAMA The Journal of the American Medical Association, found that in the month or two afterward, some 4.3 percent of the general population had signs of PTSD. The more graphic television coverage of the attacks a person had watched in the intervening time, the more likely they were to report the major symptoms.