Bullies are often popular and viewed as cool, according to new research.

More than one in five 12-year-olds are repeatedly either bullies, victims or both, and the 7 percent who are bullies are psychologically strong, researcher Jaana Junvonen, a psychology professor at UCLA, said.

"They don't show signs of depression or social anxiety and they don't feel lonely," Junvonen said.

"We hope that these findings help us dispel the myth that bullies suffer from low self-esteem," Juvonen, who works as a consultant to Los Angeles elementary schools on developing anti-bullying programs. "Our data indicate that bullies do not need ego boosters. Unfortunately, this myth is still guiding many programs conducted in schools. Instead, we should be concerned about the popularity of bullies and how to change the peer culture that encourages bullying."

Depression, social anxiety and loneliness are common among victims of bullies, who are 9 percent of the students in the UCLA study.

"Many of the victims are disengaged in school," she said.

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The professor said that programs need to focus on helping victims develop strategies to stop bullying.

She said that students who witness bullying often encourage bullies by watching someone getting pushed around or called names or helping a classmate spread rumors about another student. Bystanders rarely intervene. Juvonen regards this as one of the biggest challenges for effective anti-bullying intervention.

"Bully-victims," the six percent of students who both bully and get bullied, are the most disturbed group of all, Juvonen and her colleagues found. They are by far the most unpopular students, least engaged in school, most disruptive in class and they also reported somewhat elevated levels of depression and loneliness, Juvonen said. Teachers ranked these "bully-victims" as having by far the most conduct problems.

Bullying includes physical aggression, verbal harassment and public humiliation. Bullying occurs across ethnic groups and income brackets, and the problems associated with bullying are similar across these groups, Juvonen said.

Boys are twice as likely to be bullies as girls, almost twice as likely to be victims of bullies, and more than three times as likely to be in both categories.

"Both boys and girls can be mean and use a variety of tactics to intimidate or humiliate one another," Juvonen said.

In the study, bullying is defined as "starting fights and pushing other kids around," "putting down and making fun of others," and "spreading nasty rumors about others."

Other studies have shown that bullies are significantly more likely to engage in antisocial behavior later in life, particularly assaults and rapes, Juvonen said.

Juvonen advises parents to talk with their children about bullying before it ever happens.

"If you've never discussed this issue with your child, it might be difficult for your child to tell you about it," she said. "The older children get, the harder it is for them to bring it up."

The study, "Bullying Among Young Adolescents: The Strong, the Weak and the Troubled," was published in the December issue of the journal Pediatrics. It is part of a long-term examination of 1,900 sixth graders, and their teachers, in 11 Los Angeles-area public middle schools with predominantly minority and low-income students.