In announcing President Obama’s plans to commemorate the ten-year-anniversary of Hurricane Katrina on Thursday, the White House said the president and his cabinet members would tour areas of the Gulf Coast that were pummeled by the disaster to “highlight some of the many remarkable recovery and resilience stories across the region.”

Americans love stories of resilience, stories of people who somehow find the inner strength to not merely survive or bounce back from devastating trauma, but to thrive, flourish and “bounce forward,” as some psychologists describe the phenomenon. Who hasn’t heard Nietzsche’s dictum “That which does not kill us makes us stronger?”

And the notion of “post-traumatic growth,” as opposed to post-traumatic stress and other mental scars left on the survivors of catastrophes like Katrina, has recently become a popular, if controversial, subject in psychology.

Resilience, so often and rightly celebrated, is complicated. The questions of who can overcome, who cannot, and why, have no simple answers, though many researchers have been tackling them in recent years.

During a visit to New Orleans on Thursday, President Obama hailed the city for the progress it has made rebuilding since Hurricane Katrina struck in 2005. (Reuters)

Prompted in large part by the Sept. 11th terrorist attacks in 2001 — although early research on resilience was inspired by the stories of breast cancer survivors — a large body of work has emerged examining the concept and experience of resilience. Psychologists and other social scientists have identified multiple factors that influence what happens to people after catastrophic events.

One key to understanding responses is the nature of the event itself.

“Not all events are created equal,” said Roxane Cohen Silver, a professor of psychology at the University of California, Irvine.

Individuals and communities tend to experience more negative consequences and have an especially hard time recovering from man-made disasters like the terrorist attacks on New York and Washington, the Boston marathon bombing or the massive BP oil spill in the Gulf of Mexico in 2010, researchers say. But natural disasters like hurricanes, earthquakes, floods and wildfires can be different.

Notably, Hurricane Katrina, which killed 1,800 people and displaced hundreds of thousands, is considered both a natural and a man-made disaster. That is largely because after the storm made landfall, breaches of the man-made levees intended to guard against flooding led to the widespread destruction.

Some of the questions that can determine how survivors will respond and recover include: Was the event an “act of God” or Mother Nature — an anticipated disaster linked to geography, like hurricanes along the Gulf and Atlantic coasts and wildfires in California? Or was it entirely unexpected, like the 2012 shooting inside a movie theater in Aurora, Colo. that killed 12 people and injured more than 70 others in a place that most people would assume is safe?

Was there someone to blame, like Osama bin Laden or other terrorists, or the different shooters who killed 32 people in 2007 at Virginia Tech; the 20 children and six adults in 2012 at Sandy Hook Elementary school in Newtown, Conn.; and the nine people gunned down in June while worshipping in their church in Charleston, S.C.?

With blame, and possibly a sense of injustice, comes anger, a potential obstacle to recovery from trauma and resilience. (The opposite, forgiveness, can be one of the strongest signs of resilience, experts say, but it is often extremely difficult for victims to practice.)

“Anger can be a real hurdle to get over,” said Russell T. Jones, a professor of psychology at Virginia Tech. “The degree of anger that one might have can really inhibit an individual from seeking help. They become so angry, they just are unable to try to understand it, process the anger and move through it.”

An example of the different responses to disasters lies in the Gulf region itself, said David Abramson, Director of the Program on Population Recovery and Resiliency at New York University, who has spent years researching the impact Katrina has had on children in particular in an ongoing study.

People whose livelihoods in fishing were destroyed by the 2010 BP oil spill have had a harder time recovering mentally and “getting back on their feet,” after that disaster than many did after from Katrina, he said.

“People may be less afraid of earthquakes, even if they can cause the same level of profound damage, destruction and death,” he said, than, say, something like the Sept. 11th terrorist attacks, because “those things that are totally unexpected and that come from other human agents introduce the notion of evil, which becomes much scarier.”

Jones was a co-author of a study examining the impact of Katrina on the mental health of residents during the year following Katrina. The study showed a surprising finding — and an early sign of resilience: the prevalence of suicidal ideation, the desire to die and possible planning of one’s death, was significantly lower after the disaster than before.

The study included a comparison between data from mental health surveys before Katrina of two census tracts that were later hit hard by the hurricane and a survey of residents in the same areas during the year after Katrina.

Researchers concluded that while the prevalence of mental illness, such as PTSD and depression, doubled among the study subjects in the wake of Katrina, an unexpectedly low prevalence of suicidal ideation was a sign that “post-traumatic personal growth” was happening for survivors.

Since then, the concept of post-traumatic growth or P.T.G., has taken off, suggesting that people tend to make positive changes in their lives as a result of trauma and disaster — and that Nietzsche may have been right. The term was officially coined by Richard Tedeschi at the University of the North Carolina, Charlotte.

According to this view of trauma, not only are people more likely than previously believed to grow as a result of disaster, but also those who surmount extraordinary life challenges are more likely to find personal strength, experience spiritual change and an appreciation of life than those who have faced no traumas at all.

Some psychologists have concerns about this new focus in trauma and resilience research.

Silver, the University of California psychologist, cautioned that the growing emphasis on P.T.G. has the potential to imply that there is something inherently wrong with those who do not thrive in the face of adversity. If taken too far, the idea can wind up blaming the victim, she said.

“Thousands of people encounter different kinds of events at different times in their lives,” Silver said. “People learn something from each event to which they are exposed, learn something about the world, about the way in which they come to terms with each event. Anything that suggests there is something wrong with the person who doesn’t bounce back, that makes me very nervous.”

Silver is a co-author of a multiyear study “Whatever Does Not Kill Us: Cumulative Lifetime Adversity, Vulnerability and Resilience,” that found a key factor in predicting a negative impact on the well being of victims and survivors was previous exposure to trauma. Some examples include the loss of a parent, physical and sexual abuse, illness, homelessness and natural disasters.

So if someone in New Orleans had already survived, say, rape or cancer, or had a history of repeated trauma and then lost everything because of Katrina, he or she could be more likely to have a harder time coping mentally with what the hurricane wrought than someone with no previous history of trauma.

However, the study also found that people with “a history of some lifetime adversity” handled traumatic events better than people with no history of adversity and lots of history. In other words, prior bad experiences and trauma — but only in moderation — could prepare someone for a trauma or disaster, laying the groundwork for resilience.

There are varying estimates of the percentages of people who will meet the psychiatric criteria for PTSD in the aftermath of tragedy. Jones said that between 60 and 80 percent of individuals will experience at least one major traumatic event in their lives, but only between 8 and 15 percent are likely to develop PTSD.

In mid-April of 2007 the professor was scheduled to fly to the Gulf region to continue his trauma and disaster preparedness work with children, teaching them how to prepare for storms. He was headed for a school in Pearlington, Miss., a tiny bayou town ravaged by Katrina. But as he was packing for the trip, he heard the news that a mass shooting was unfolding on a day of bloody horror at his own campus in Blacksburg, Va.

He quickly cancelled his trip to New Orleans, scheduled for the day after the shootings, and rushed to the scene. Jones has since expanded his trauma research to include the Virginia Tech rampage and other shootings.

One key finding of his research on the Virginia Tech and Colorado shootings was that in some cases family members of those killed, the injured and others who were traumatized by witnessing the events, avoided or delayed seeking help. People have waited for years to seek treatment from mental health professionals for anxiety, insomnia, nightmares, and problems with relationships and work, Jones said, which may lead them to a breaking point.

On the other hand, in more than 30 years of researching disasters and trauma, Jones said he had also seen striking signs of resilience.

“People became more spiritual or religious,” he said. “They had a deeper meaning and purpose in life, they were discovering inner strength.”

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