Robert Bond, associate professor, was the lead author of a study that provides some of the best evidence to support violence spreads like a contagious disease among adolescents. 

The study found teenagers were up to 183 percent more likely to carry out acts of violence if one of their friends also committed the same act. However, the spread of violence doesn't stop at friends; the results suggested the contagion extends up to four degress of separation. For example, the violence can spread from a person to a friend, to the friend's friend and two more friends beyond. 

"This study shows just how contagious violence can be," Bond said. "Acts of violence can ricochet through a community, traveling through networks of friends." 

Bond conducted this study with Brad Bushman, professor of communication and psychology at Ohio State. Their results appear online in the American Journal of Public Health. 

These results are similar to studies that show characteristics from happiness to smoking spread within social networks, at about the same rates found in this research. 

"We now have evidence that shows how important social relationships are to spreading violent behavior, just like they are for spreading many other kinds of attitudes and behaviors," Bushman said. 

More results from this study are featured in an Ohio State news release.