Bullied children could experience higher rates of chronic inflammation; these effects could last into adulthood.

"Our findings look at the biological consequences of bullying, and by studying a marker of inflammation, provide a potential mechanism for how this social interaction can affect later health functioning," William E. Copeland, Ph.D., associate professor of psychiatry and behavioral sciences at Duke University School of Medicine and the study's lead author said in a news release.

Past studies have found victims of bullying often suffer social and emotional problems in adulthood, but many of these individuals report pain and illness susceptibility as well.

"Among victims of bullying, there seems to be some impact on health status in adulthood," Copeland said. "In this study, we asked whether childhood bullying can get 'under the skin' to affect physical health."

Researchers looked at the Great Smoky Mountains Study, which followed 1,420 individuals over 20 years. The participants were interviewed from childhood to young adulthood about their experiences with bullying.

The study also collected blood samples to test for C-reactive protein (CRP), which is a marker of inflammation.

"CRP levels are affected by a variety of stressors, including poor nutrition, lack of sleep and infection, but we've found that they are also related to psychosocial factors," Copeland said. "By controlling for participants' pre-existing CRP levels, even before involvement in bullying, we get a clearer understanding of how bullying could change the trajectory of CRP levels."

The participants were split into three groups: victims of bullying, bullies, and those who had been on both sides of the spectrum.

The team found victims of bullying had higher CRP levels than those in other groups. CRP appeared to rise with each time the victim was bullied. Bullies were found to have the lowest CRP levels.

"Our study found that a child's role in bullying can serve as either a risk or a protective factor for low-grade inflammation," Copeland said. "Enhanced social status seems to have a biological advantage. However, there are ways children can experience social success aside from bullying others."