A new study upends the notion that the effects of bullying are confined to childhood.

Children who are bullied are more likely to have serious mental and physical health problems as adults and less likely to hold steady jobs or develop meaningful relationships with family and friends, according to a new study on the lingering effects of bullying.

The findings contradict the widespread belief that bullying is a temporary problem that "gets better" with age, suggesting it is not just a "harmless rite of passage, but throws a long shadow over affected people's lives," as the researchers put it.

"We cannot continue to dismiss bullying as a harmless, almost inevitable, part of growing up," Dieter Wolke, one of the study's authors, said in a press release. "We need to change this mindset and acknowledge this as a serious problem for both the individual and the country as a whole; the effects are long-lasting and significant."

In a study published this week in the journal Psychological Science, researchers from the University of Warwick and Duke University Medical Center tracked the health of more than 1,400 North Carolina children between the ages of 9 and 13 starting back in 1993. Researchers evaluated the health of those subjects every year until age 16, and then again at 19, 21, and 24 to 26. Parents were asked throughout the study if their children had been bullied, or had bullied others.

Children who were victims of bullying were far more prone to obesity and serious health problems as adults — including diabetes and cancer — than their peers. They were also more likely to report difficulties with forming long-term friendships and holding steady jobs.

Worse off were children who both bullied and were bullied — "bully-victims" as the study called them. Bully-victims were six times as likely as their peers to smoke cigarettes, suffer from diabetes, and develop cancer (possibly as a result of their comparatively high smoking rate). They were also six times more inclined to develop a psychiatric disorder, and more likely to be arrested for felonies.

A 2011 report from the Centers for Disease Control and Prevention found that 30 percent of all American adolescents reported either being victims or perpetrators of at least "moderate bullying." Of that group, 6 percent reported that they both bullied and were bullied.

While the findings about bully-victims could ostensibly be dismissed as the result of other factors — studies have shown bullies are more likely to have troubled home lives that could lead to social and health issues later in life — the researchers noted that their findings retained their integrity even after controlling for those familial variables.

"Thus it is being bullied that leads to the ill effects over and beyond any other disadvantages," Wolke told Forbes.

While copious studies and news reports have detailed the effects of bullying on adolescents, bullying's lasting effects have received comparatively scant attention. However, a number of recent studies have begun to show how bullying can lead to significant, hidden problems later in life, suggesting that more should be done to prevent bullying in the first place.

A study published in June linked sibling bullying to lasting depression and anxiety, thought it stopped short of citing bullying as the only cause of those subsequent mental health issues. A separate study also released this year found that bullied students were more likely to suffer from depression and have suicidal thoughts in adulthood.

"Some interventions are already available in schools but new tools are needed to help health professionals to identify, monitor, and deal with the ill effects of bullying," Wolke said. "The challenge we face now is committing the time and resources to these interventions to try and put an end to bullying."