DENVER—Studying extreme events in disaster settings allows us to study them in their most pure form, because disaster settings are equal opportunity events that affect people cross-sectionally in representative populations,” said Carol S. North, MD, MPE. Dr. North, Professor of Psychiatry at Washington University School of Medicine, St. Louis, addressed the topic of the neuropsychiatric effects of terrorism in her presentation at the 54th Annual Meeting of the American Academy of Neurology. “The Washington University disaster research team has been studying disasters for two decades,” she said. “We’ve been to natural disasters, including tornadoes, earthquakes, and flooding. We’ve been to technological disasters, including a plane crash into a hotel in Indianapolis. We’ve been to a series of acts of terrorism, including some shooting sprees, the bombing of the Federal Building in Oklahoma City, and the bombings of US embassies in East Africa.”

The team has employed the same diagnostic instruments to systematically study more than 2,000 survivors of the direct disaster region from more than a dozen disaster sites. “We followed them for between one and three years, and in one case for up to 12 years,” Dr. North noted. Based on these results, “we can now begin comparing the effects of different disasters,” she said.

POSTTRAUMATIC STRESS DISORDER IN THE DISASTER SETTING

Dr. North began her lecture by elaborating on posttraumatic stress disorder. “The first hurdle before making the diagnosis is determining if the right kind of event has occurred and if the person has been exposed to it,” she said. The event must be one that poses a threat to life and evokes responses of terror and horror in its victims. “Once you’ve established that the person was exposed to the right kind of event, then there are three groups of symptom criteria that a person has to meet,” she continued. “They’re called the B, C, and D symptom criteria. The B symptoms are called intrusive reexperience, and this is the stuff of nightmares and flashbacks and intrusive, unwelcome memories that keep popping into people’s minds unwanted.”

The group C symptoms are “avoidance and numbing. These are when people are so overwrought with their symptoms that they can’t cope. They ‘check out’ emotionally. They don’t want to think about it; they don’t want to be reminded of it. Their emotions may be numb, and they may feel distant and isolated from other people.”

The group D symptoms are the hyperarousal symptoms, “when people are very keyed up and on edge. They may be jumpy and easily startled. They have trouble concentrating, and they may not sleep well,” Dr. North explained.

“One thing to note about these symptoms is that they have to be new symptoms,” she added. “Many of these symptoms are endemic in the population. Unfortunately, much of the research into these symptoms uses scales that don’t differentiate new symptoms associated with a disaster event from symptoms that are in the population, and so they may overestimate the rates of posttraumatic stress disorder.”

Likewise, the symptoms must also go on for at least a month before posttraumatic stress disorder can be diagnosed, Dr. North noted. “And just having the symptoms isn’t enough—they must also have a significant effect on people’s lives.”

Oklahoma City, April 19, 1995

“At its time, the Oklahoma City bombing was the most severe act of terrorism ever on American soil,” Dr. North said. “There were 167 people killed in the explosion and about 600 injured. The explosion was quite capricious in that there were people who were uninjured surrounded by people who died.

“Some of the data I’ll be presenting have been published in the August 25, 1999, JAMA. We were able to obtain a very good sample. The Health Department had put together a registry of victims, and we obtained a random sample of this registry. A third of our sample was in the Murrah building, and the other people in the sample were in other heavily damaged buildings or outside. This was a heavily impacted sample in the direct path of the bomb blast, evidenced by the fact that 87% of our sample had been injured.

“We interviewed 182 survivors and did a follow-up study in which we were able to reinterview three quarters of our sample. Our participation rates were not as high as usual because of the extremely sensitive and clinical nature of the setting,” Dr. North said. “We entered the disaster field four months after the disaster, and it took us four months to enter the data, so we completed the interviews an average of six months after the disaster. We also conducted a follow-up study almost one year later.”

The sample was about half female, largely Caucasian, average age 43, with two years of college, and about two thirds were currently married. Dr. North and her colleagues used the Diagnostic Interview Schedule—which provides structured psychiatric diagnoses—as the basis for their data collection. “We were able to make diagnoses of disorders that occurred after the bombing and retrospectively obtain information about psychiatric disorders that were present before the bombing,” she explained. “The Disaster Supplement obtained information about people’s exposure to disaster and other variables of relevance to the disaster experience.”

DATA FROM THE DISASTER

“The first thing to recognize is that, despite the severity of this disaster, about half the sample did not meet the criteria for psychiatric disorders afterwards, speaking to the resiliency of the human spirit,” Dr. North observed. “We diagnosed posttraumatic stress disorder in over a third of the sample.” About two thirds of the time, the posttraumatic stress disorder “was accompanied by baggage of other comorbid psychiatric disorders,” she added.

“There were also a few other psychiatric disorders in people who did not have posttraumatic stress disorder. The second most common diagnosis was major depression. There were a few other anxiety disorders and a few alcohol and drug use disorders. About a third of the sample had a non–posttraumatic stress disorder, and there were a few unusual people who were in the bombing who didn’t get posttraumatic stress disorder because of the bombing but got posttraumatic stress disorder because of some other event after the bombing, leaving a 34% rate of posttraumatic stress disorder specific to the bombing.

“We also had prospective information on disorders that were present before the bombing, and the majority of people with a disorder afterward had experienced the disorder previously. We found no incident drug or alcohol disorders after the bombing. The bombing did not cause people to go out and drink or abuse drugs to the extent of developing new addictions.

“This isn’t the whole story, however,” she added. “There were also disorders present prior to the bombing that were not present after. So you really have to look at the whole picture to determine the significance of these incident disorders.”

SYMPTOMS AND PREDICTORS

The most common individual symptoms of posttraumatic stress disorder after the Oklahoma City bombing were intrusive memories, trouble sleeping, trouble concentrating, and being jumpy or easily startled. The least common symptoms were psychogenic amnesia and numb emotions or restricted affect. “Almost everybody reported that they had at least one symptom. About 80% of people met B and D criteria for posttraumatic stress disorder. Having these kinds of symptoms was the norm. However, meeting group C criteria was a lot less common, and people who met group C criteria almost always met full criteria for posttraumatic stress disorder,” Dr. North observed. “The C criteria were like a gatekeeper or marker for posttraumatic stress disorder, being 100% sensitive and 94% specific for posttraumatic stress disorder,” she commented.

“I thought these C symptom criteria were important enough to examine in comparison to other variables. I found that people who met those C criteria were significantly more likely to have a comorbid psychiatric disorder, to have a pre-disaster disorder, and to seek mental health treatment compared to people who did not meet the C criteria. Meeting the B or D criteria in the absence of meeting the C criteria did not have the same associations.”

In addition, Dr. North looked through the data to determine what predictors she could find for posttraumatic stress disorder. “These are the only variables that predicted it: Women had about twice the risk of posttraumatic stress disorder as men, and people with preexisting disorder had about twice the rate of posttraumatic stress disorder as those without,” she said. Lower educational level, having more injuries, losing more loved ones, and other life events were also predictive.

However, Dr. North said, “when I examined all of our variables in one regression model, it turned out there were confounders, so we were left with only four predictors of posttraumatic stress disorder: being female, having a pre-existing disorder, injuries, and loss of loved ones.”

FOLLOWING THE FALLOUT

“When we returned around a year later for follow-up, the rates of psychiatric disorders found at index and those found at reassessment looked pretty consistent,” said Dr. North. “But on a case-by-case basis, what we found was that people told us different things at different times, so that when I gathered together all of the data, the rates [of psychiatric disorders] were actually higher. We had a 41% rate of posttraumatic stress disorder, and over half of the sample had some psychiatric disorder. There was some recovery or healing over that time, so most of the major depression cases were recovered,” she noted, “but the majority of the posttraumatic stress disorder cases were not. Most of the people suffering with any disorder were suffering with posttraumatic stress disorder.”

When asked when their posttraumatic stress disorder started, 76% of people with the disorder said it started the same day as the bombing; 94%, within that week; and 98%, within the same month, Dr. North said. “Nobody told us that their posttraumatic stress disorder had started after that six-month definition for delayed posttraumatic stress disorder.”

At follow-up, “we found 12 cases with posttraumatic stress disorder that had not presented with it at the initial testing. All of them said their symptoms had started early. None of them said their symptoms had started more than six months after the bombing. So rather than delayed cases, these cases were subthreshold,” she elaborated. “Looking at the data, we saw that these people almost met the criteria [at baseline] but lacked one or two C symptoms and over the course of the year developed those symptoms and went on to meet the criteria for posttraumatic stress disorder.

“Also, when we asked people how long their posttraumatic stress disorder lasted, most of the people were still suffering with it,” Dr. North added. “So by definition, all of our cases were chronic, just as none of them were defined as delayed.”

DEALING WITH THE DATA

“The clinical indications of this study are that we need to subdivide the population into those who are psychiatrically ill and those who are not,” said Dr. North. “The latter I call subdiagnostically distressed. We make this dichotomy to direct people to interventions or treatments that are appropriate to their needs.” To accomplish this, Dr. North stated, “our data would suggest that we should focus on those with prominent avoidance and numbing [group C] symptoms, because they virtually defined posttraumatic stress disorder. We would triage those people for psychiatric evaluation and management, and it turned out that the group C symptoms defined who was likely to get posttraumatic stress disorder, and the disappearance of those symptoms over time also very much paralleled recovery.

“Another thing the data teach us is that posttraumatic stress disorder in disaster settings is a complex disorder,” Dr. North continued. “The lesson learned is that once you make a diagnosis of posttraumatic stress disorder, don’t stop looking, because there’s likely to be another disorder that might be at least as important to the treatment and outcome.”

Additionally, while it is important to not forget people’s resiliency after severe disasters, “at the same time we don’t want to discount the suffering of those who are in subdiagnostic distress. These individuals have prominent intrusion and hyperarousal symptoms but not avoidance and numbing symptoms. These people can be reassured that their distressing symptoms are normal responses to abnormal events and that they are likely to recover with the aid of talking about it with trusted others, by cognitively processing it, and by gaining perspective in their lives,” Dr. North said.

NEW YORK CITY, SEPTEMBER 11, 2001

“Now what does all this have to do with September 11?” Dr. North asked. “When we look at the mean rates of posttraumatic stress disorder by disaster type, we see that terrorism had the highest rate of posttraumatic stress disorder associated with it, so we can try to extrapolate what we know from Oklahoma City to help us understand what our health needs are in New York and Washington. But there are differences—important differences. The September 11 events were obviously much larger in scope and magnitude, striking at the nerve center and the symbols of our nation, making us feel particularly vulnerable,” she noted.

Also, “on September 11, there were relatively fewer injuries among those who survived, but there were so many more deaths that there will be much more bereavement, particularly among the firefighters who lost so many of their colleagues. The live television coverage and the repeated scenes of the planes flying into the buildings has helped stir up symptoms, and then there are other events, such as economic effects, anthrax attacks, and other threats, that are also likely to keep symptoms alive,” she added.

“So, what are the implications of September 11? There are a few generalizations that we might make. It might be helpful to divide the population into those who are psychiatrically ill and those who are subdiagnostically distressed so that we can provide the most appropriate intervention for the psychiatric needs of the individuals,” Dr. North postulated. “Many people won’t get treatment at all, or they’ll delay in seeking treatment, so we may have to go on case-finding exercises to find people who are in need. We know that posttraumatic stress disorder can be very chronic, so we’re going to want to stay there for the long haul for the people as their need continues.”

—C. Justin Romano

Suggested Reading
North CS, Nixon SJ, Shariat S, et al. Psychiatric disorders among survivors of the Oklahoma City bombing. JAMA. 1999;282:755-762.

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