Years after the September 11 terrorist attacks, some 19% of 43,032 adults who directly witnessed the attacks still screened positive for stress symptoms, according to a recent study published in the Journal of the American Medical Association.
These symptoms were indicative of probable post-traumatic stress disorder, according to the authors from the New York City Department of Health and Mental Hygiene, which collected these data in 2006-2007.
But many people are resilient after upsetting events, says George Bonanno, a professor at Columbia University. In his work on how people cope with negative events, from the 2001 terrorist attacks to marital woes, he finds that individuals have different trajectories. One group reacts particularly badly — these people are the ones likely to develop PTSD — but then “you always get some people who are not affected by symptoms,” Bonanno told us.
Why some people are more resilient than others isn’t clear, Bonanno says. But across many of his studies, he finds the same pattern: the percentage of people with PTSD never goes higher than about 30% in the study population, and the number who are resilient never dips below 30%.
He also points out that you can be resilient but still experience one or even two stress symptoms, like having trouble sleeping. “The healthy population is not necessarily all symptom-free,” he says. “Having some symptoms is not diagnostic of anything.”