Six-year-olds who are more intelligent than their peers may be less likely to experience trauma by age 17, and if they do, they may be less likely to develop posttraumatic stress disorder (PTSD), according to a report in the November issue of Archives of General Psychiatry. In contrast, children who have anxiety disorders and conduct problems at age 6 appear more likely to develop PTSD following exposure to traumatic events.

Researchers currently believe that certain factors, including gender, race, and socioeconomic background, may predispose individuals to experience trauma and also increase their risk of PTSD once they are exposed to trauma.

These factors may be more important than the type or severity of the trauma experienced, in determining who is at risk for PTSD.

Naomi Breslau, PhD, and her colleagues at Michigan State University in East Lansing arrived at this theory after studying 713 children (336 boys and 377 girls) born between 1983 and 1985.

Since socioeconomics was a component of the study, the researchers took into account the hospitals in which the children were born; one was located in a disadvantaged, urban area, while the other was located in a middle-class, suburban area.

Beginning at age 6, the children were given intelligence tests by the researchers. From there, the children’s teachers rated their behavior at school, while parents reported any symptoms of anxiety disorders, including phobias, separation anxiety, and generalized anxiety disorder.

At age 17, the participants completed an interview designed to measure the number and type of traumatic events they had experienced in their lives and also how deeply those events affected them, including whether they had ever experienced symptoms of PTSD.

The socioeconomic and gender contrast provided Dr. Breslau and colleagues with interesting results. "As in previous studies, the cumulative incidence of exposure to traumatic events was higher in inner-city youth than in suburban youth," said the authors, who found that during childhood and adolescence, 541 (76%) of the participants had experienced a traumatic event, and upon assessment, 45 (6%) met the criteria for PTSD. Dr. Breslau and colleagues also found that the cumulative occurrence of exposure to any traumatic event was higher in the urban subset than in the suburban subset (86% versus 65%, respectively). The most common traumatic event was learning of a sudden or unexpected death of a close friend or relative, with 50% of the sample having experienced that kind of event.

The investigation showed that there was a correlation between traumatic events and gender, as well.

"We observed in these data the sex-related pattern reported in previous studies, with males more likely to be exposed to trauma, and females more likely to experience PTSD following exposure," explained Dr. Breslau et al.

In addition to socioeconomic and gender factors, the researchers found that the children who had an IQ above 115 at age 6 were less likely to be exposed to any type of trauma, especially violent assaults, and were less likely to develop PTSD by age 17, even if they had other factors, such as anxiety disorders and an urban background, stacked against them.

In regard to conduct, the researchers found that participants with more conduct problems than normal at age 6, as reported by their teachers, had a higher risk of being exposed to violent crime, such as rape, mugging, or beating, by age 17.

"The ways in which high IQ might protect from the PTSD effects of traumatic exposure are unclear," said Dr. Breslau and colleagues. "The findings underscore the importance of investigating cognitive processes in a person’s responses to challenging and potentially traumatic experiences and the involvement of general intelligence in shaping them."

—Tara Hayden

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