The new study, published in the journal JAMA Psychiatry on Wednesday, is the most comprehensive effort to date to establish the long-term consequences of childhood bullying, experts said.
"It documents the elevated risk across a wide range of mental health outcomes and over a long period of time," said Catherine P. Bradshaw, an expert on bullying and a deputy director of the Center for the Prevention of Youth Violence at Johns Hopkins University, who was not involved in the study.
"The experience of bullying in childhood can have profound effects on mental health in adulthood, particularly among youths involved in bullying as both a perpetuator and a victim," she added.
The study followed 1,420 subjects from western North Carolina who were assessed four to six times between ages 9 and 16. Researchers asked both the children and their primary caregivers if they had been bullied or had bullied others in the three months before each assessment. Participants were divided into four groups: bullies, victims, bullies who also were victims, and children who were not exposed to bullying.
Participants were assessed again in young adulthood - at 19, 21 and between 24 and 26 - using structured diagnostic interviews.
Researchers found that victims of bullying in childhood were 4.3 times more likely to have an anxiety disorder as adults, compared with those with no history of bullying or being bullied. Bullies who were also victims were particularly troubled: they were 14.5 times more likely to develop panic disorder as adults, compared with those who did not experience bullying, and 4.8 times more likely to experience depression.
Men who were both bullies and victims were 18.5 times more likely to have had suicidal thoughts in adulthood, compared with the participants who had not been bullied or were perpetrators. Their female counterparts were 26.7 times more likely to have developed agoraphobia, compared with children not exposed to bullying. Bullies who were not victims of bullying were 4.1 times more likely to have anti-social personality disorder as adults than those never exposed to bullying in their youth.
The effects persisted even after the researchers accounted for pre-existing psychiatric problems or factors that might have contributed to disorders, like physical or sexual abuse, poverty and family instability.
"We were actually able to say being a victim of bullying is having an effect a decade later, above and beyond other psychiatric problems in childhood and other adversities," said William E. Copeland, lead author of the study and an associate professor of psychiatry and behavioral sciences at Duke University Medical Center.
Bullying is not a harmless rite of passage, but inflicts lasting psychiatric damage on a par with certain family dysfunctions, Copeland said. "The pattern we are seeing is similar to patterns we see when a child is abused or maltreated or treated very harshly within the family setting," he said.
One limitation of the study is that bullying was not analyzed for frequency, and the researchers' assessment did not distinguish between interpersonal and overt bullying. It only addressed bullying at school, not in other settings.
Most of what experts know about the effects of bullying comes from observational studies, not studies of children followed over time.
Previous research from Finland, based on questionnaires completed on a single occasion or on military registries, used a sample of 2,540 boys to see if being a bully or a victim at 8 predicted a psychiatric disorder 10 to 15 years later. The researchers found that frequent bullying victims were at particular risk of adverse long-term outcomes, specifically anxiety and anti-social personality disorders. Victims were at greater risk for anxiety disorders, while bullies were at increased risk for anti-social personality disorder.
© 2013, The New York Times News Service