Bullying casts a long shadow. Children who are bullied are more prone to depression and suicidal tendencies even when they grow up; they're also more likely to get sick and have headaches and stomach troubles, researchers have discovered. A new study may have found the underlying cause: A specific indicator of illness, called C-reactive protein (CRP), is higher than normal in bullying victims, even when they get older. In contrast, the bullies, by the same gauge, seem to be healthier.
The researchers focused on CRP because it's a common, easily tested marker of inflammation, the runaway immune system activity that's a feature of many chronic illnesses including cardiovascular disease, diabetes, chronic pain, and depression, explains lead author William Copeland, a psychologist and epidemiologist at Duke University Medical Center in Durham, North Carolina.
To link inflammation to bullying, the researchers asked 1420 youngsters between the ages of 9 and 16 whether, and how often, they had been bullied or had bullied others. Interviewers asked participants whether they felt more teased, bullied, or treated meanly by siblings, friends, and peers than other children—and whether they had upset or hurt other people on purpose, tried to get others in trouble, or forced people to do something by threatening or hurting them. The researchers took finger stick blood tests at each assessment. Interviews took place once a year until the participants turned 16, and again when they were 19 and 21. The children interviewed were participants in the larger Great Smoky Mountains Study, in which some 12,000 children in North Carolina were assessed to track the development of psychiatric conditions.
In the short term, the effect of bullying on the victims was immediate. CRP levels increased along with the number of reported bullying instances , and more than doubled in those who said they'd been bullied three times or more in the previous year, compared with kids who had never been bullied. No change was seen in bullies, or in kids who hadn't been involved with bullying one way or the other, the researchers report online today in the Proceedings of the National Academy of Sciences.
The real eye opener, Copeland says, was the change in CRP in the 19- and 21-year-olds. Levels of the protein increased over time in all groups, which is normal. But the increase was sharper in the bullying victims: Even 10 years later, average CRP levels were still higher (more than 1.5 mg/L) than in those who had never been bullied (about 1 mg/L). In the bullies, the levels were about 0.5 mg/L, slightly less than half that of the victims. The CRP differences between bullies and victims remained even when the researchers accounted for potentially confounding factors, such as mental disorders, substance abuse, and other forms of stress.
Elevated CRP may be a specific route through which childhood stress leads to health problems down the road, the researchers conclude. Adults who were abused as children also show increased inflammation, as measured by CRP levels, in some studies.
Despite the implied health benefits of bullying, Copeland doesn’t advocate picking on people to better your health. The advantage probably doesn't lie in the aggression itself, but rather in the heightened control, power, and social status that bullies enjoy, he believes.
The benefits of bullying are dispiriting but not surprising, says biological anthropologist Thomas McDade of Northwestern University in Evanston, Illinois. The slower-than-normal increase of CRP in bullies supports a growing mound of research showing that those at the top have it better, he says.
A key strength of the new study, McDade says, is that it focuses on a specific measurement, checked repeatedly over time. "CRP is clearly one way in which social environment can get under one's skin"—affecting health for better or worse, he says.
Because inflammation is an underlying factor in so many chronic diseases, the fact that people in their early 20s are already showing signs of inflammation is a warning bell, Copeland adds. Using data from the larger study, his team will scrutinize other measures of adversity, such as the stress hormone cortisol, and epigenetic changes  in which environmental factors affect the way genes are activated. The scientists will also look for biomarkers of more positive methods than bullying through which kids can increase their confidence and social standing.
Ideally, antibullying programs, in addition to protecting potential victims, should help the more aggressive kids find ways to enhance their social status "without wreaking havoc on others," Copeland says.