The effects of bullying in childhood can last a lifetime, both for the child who's bullied and for his or her tormenter.

But according to a Duke University study published today in the Proceedings of the National Academy of Sciences, while young adults show long-term ill effects of having been bullied in childhood, those who did the bullying might actually be healthier than their peers in one important measure.

The report is based on findings from the longitudinal Great Smoky Mountains Study, which started in 1993 and followed 1,420 children from western North Carolina. Researchers interviewed the participants at up to nine points in time, first when they were children and adolescents (aged 9 to 16) and again when they were young adults (aged 19 to 21). The study was led by William Copeland, an associate professor of psychiatry and behavioral sciences at Duke University Medical Center in Durham, North Carolina.

Earlier reports, including some from the Great Smoky Mountains Study, showed that young adults who were bullied as children can have long-term mental health problems such as anxiety disorders, panic disorder, and depression.

But this is the first indication that being the bully might actually be protective. The reason this escaped earlier notice, according to Copeland, is that previous work lumped together two kinds of bullies: those who were also sometimes bullied themselves (whom he calls bully-victims) and those who were "pure bullies."

Bully-victims "have the worst long-term emotional problems and poor health outcomes," Copeland and his co-authors wrote. By separating them out of the analysis in this new study, they wrote, it became clear that "pure" bullies "gain benefits from bullying others without incurring costs and may be healthier than their peers, emotionally and physically."

Protective Effect of Bullying?

The current study measured blood levels of C-reactive protein (CRP)—a biomarker of chronic inflammation that's been linked to cardiovascular risk and metabolic syndrome—over several points in time during childhood, adolescence, and young adulthood. CRP is a sign of stress on the body, Copeland said, and "a harbinger of health problems down the road."

CRP levels increased in all participants as the study subjects got older, the scientists found. But those who had been bullied had the highest level of increase, and former bullies had the lowest. Those who were bully-victims fell somewhere in between, at about the same level as participants who had not been involved in childhood bullying at all.

"There seems to be a protective effect for the bullies because of this enhanced social status, or their success that comes along with being a good bully," Copeland said. The pattern was present even after controlling for body mass index, substance use, health status, and exposure to other types of trauma.

But Catherine Bradshaw, deputy director of the Johns Hopkins Center for the Prevention of Youth Violence in Baltimore, Maryland, cautioned against overinterpreting the lower CRP levels in bullies. Rather than a health benefit, the lower CRP levels might just reflect a difference in the bullies' underlying biology, not unlike biological differences that have been seen elsewhere in children and adults with patterns of aggressive behavior.

And even if the Duke findings are evidence that being a bully might be good for people, at least along this one dimension, it shouldn't be read as a license to bully, she said.

There are "well-documented studies, both short- and long-term, showing that kids who are involved in bullying do have other problematic outcomes," Bradshaw said. For instance, children who bully are more likely to be members of gangs, carry a weapon, and have truancy problems.

Copeland added that the enhanced social status of bullies that he believes might account for their lower CRP levels can and should be achieved in more morally acceptable ways. Varsity sports, anyone?