Anti-bullying policies in most U.S. states aim to protect kids against abuse from their peers in school and online, but their effectiveness varies widely depending on where students live, a study suggests.

Researchers analyzed survey data on bullying from almost 62,000 students in grades 9 through 12 to see how their experiences varied based on the type of law on the books in their home state.

In states where the laws followed at least one U.S. Department of Education (DoE) recommendation for anti-bullying policies, teens were 24 percent less likely to report bullying and 20 percent less likely to report cyber-bullying, the study found.

The DoE recommends, for example, that laws include explicit descriptions of prohibited behaviors and spell out clear reporting practices and specific consequences.

"Although anti-bullying policies by themselves can't eradicate bullying, these results suggest that such policies are an important part of a comprehensive strategy for preventing bullying among youth," said lead study author Mark Hatzenbuehler, a public health researcher at Columbia University in New York.

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Bullying is one of the most common forms of peer aggression in schools, and both perpetrators and victims may experience mental health problems linked to this behavior such as anxiety, depression or social isolation, Hatzenbuehler and colleagues note in JAMA Pediatrics.

Researchers examined student survey responses about bullying in 25 states and DoE assessments of anti-bullying policies in those states for 2011.

Reported bullying rates ranged from about 14 percent in Alabama to almost 27 percent in South Dakota, with an average rate of 20 percent across all the states in the study.

Rates of cyber-bullying ranged from roughly 12 percent in Alabama to nearly 20 percent in South Dakota, with an average of about 16 percent.

The researchers also assessed the effectiveness of 16 components of anti-bullying legislation recommended by DoE. The components most strongly tied to lower rates of bullying and cyber-bullying included defining these behaviors and spelling out consequences.

Only states with laws passed prior to the survey on bullying were included in the analysis, and more research is needed to assess the effectiveness of anti-bullying legislation in all 50 states, the authors note.

Even so, previous research points to some steps schools can take to curb this behavior, said Lisa Jones, with the Crimes Against Children Research Center at the University of New Hampshire in Durham.

"Research suggests that a combination of positive school climate, trust between students and staff, clear and consistent victimization response policies, and evidence-based prevention education programs for youth can make a difference - so these are the directions schools should be heading," Jones, who wasn't involved in the study, said by email.

The most effective policies to prevent bullying will also look beyond just schools to include parents, coaches and other adults who are regularly involved with children, said Megan Moreno, a specialist in adolescent health at Seattle Children's Research Institute.

"Bullying commonly takes place in schools, but also takes place on sports teams, in Girl Scout troops, at summer camps, and within almost every youth-oriented activity," Moreno, who wasn't involved in the study, said by email.

Policing behavior that takes place online requires additional vigilance, said Dr. Matthew Davis, a pediatrician at the University of Michigan in Ann Arbor and director of the C.S. Mott Children's Hospital National Poll on Children's Health.

"One of the best ways for parents to keep kids safe from cyber-bullying is to make sure that kids know that they should tell their parents if they see something or read something online that makes them upset," Davis, who wasn't involved in the study, said by email.