(NEW YORK) -- Mental disorders plague many adults who were bullied as children, but a new study suggests that those who had mental health disorders during childhood are three times more likely to become bullies.
Researchers at Brown University analyzed survey responses from parents of nearly 64,000 children ages 6 to 17 who were identified as having a mental health disorder, and those who were identified as bullies.
An estimated 15 percent of U.S. children in 2007 were identified as bullies by a parent or guardian, according to the responses, which were part of the 2007 National Survey of Children's Health.
Those who were considered the bullies were more than twice as likely to experience depression, anxiety and attention deficit disorder. They were also six times more likely to be diagnosed with oppositional defiant disorder, characterized by ongoing episodes of anger and hostility, especially toward authority figures, such as parents, teachers or other adults.
"This study gives us a better understanding of the risk profiles of bullies," said Dr. Stefani Hines, director at the center for human development at Beaumont Children's Hospital in Royal Oak, Mich.
Hines was not involved in the study, which was presented Monday at the American Academy of Pediatrics annual meeting in New Orleans.
The findings do not surprise many experts, who say the symptoms of these disorders characterize many bullies.
According to Alan Hilfer, chief psychologist at Maimonedes Medical Center in Brooklyn, N.Y., the disorders, such as ADHD, "often lead to impulsive and at times aggressive behaviors" that are common among bullies.
Bullies often continue the cycle of social abuse that they have experienced themselves, he said.
"They can be depressed, fearful, and they often take out some of their anger and frustration on others down the pecking order," said Hilfer.
Support is often given to the bullied peers who are seen as victims, the researchers said. Many bullies should also be viewed as victims and offered help to change their behavior, they said.
"This finding emphasizes the importance of providing psychological support to not only victims of bullying but bullies as well," the researchers wrote.
The study did not look at the likelihood that bullies would have a mental health disorder, only that some children who have a disorder were more likely to be identified as bullies.
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