A long-term study shows that children who were bullied have more trouble in adulthood than children mistreated by their parents.

Peers may be worse than parents when it comes to the psychological effects of disparaging words and harassment.

A study published today in The Lancet Psychiatry reports that children who were bullied by peers had significant mental health problems as adults – even more significant than children who were mistreated by their parents or caregivers.

In his study, University of Warwick psychology professor Dieter Wolke defined maltreatment as physical, sexual, or emotional abuse by an adult caretaker.

Bullying, in contrast, is repeated aggression by peers (such as verbal taunts, physical attacks, or social exclusion) carried out at least once a week.

Wolke and his research team followed two groups of children, one in the United Kingdom and one in the United States, through childhood and into adulthood. Data on maltreatment and bullying in youth correlated to mental health problems in adulthood.

Wolke and his team found that bullied children in the U.K. experienced higher rates of anxiety than those who were mistreated by adults. In the U.S., bullied children had higher rates of depression and suicidal tendencies than maltreated children. In both groups, children who were both mistreated and bullied were more likely to suffer from mental health problems.

“The strength of our study is that we found similar findings on the effects of bullying on adult mental health in both cohorts, despite their differences in population,” Wolke said.

Get the Facts: What Is Bullying? »

One in three U.S. children report that they’ve been bullied at school, and about one in seven report online bullying.

In Wolke’s study, 30 percent of children in the U.K. group and 16 percent in the U.S. group reported bullying. An additional 7 percent of children in the U.K. and 10 percent in the U.S. reported both bullying and maltreatment.

While acknowledging that bullying is pervasive across cultures and socioeconomic groups, psychologists and anti-bullying advocates work hard to counter the perception that bullying is normal to dissuade adults from having a complacent “kids can be so cruel” mentality.

“Being bullied is not a harmless rite of passage or an inevitable part of growing up; it has serious long-term consequences,” said Wolke.

Bullying may also go unreported and could have consequences aside from mental health problems, Wolke says.

In the U.K., about 16,000 children permanently stay home from school because they are routinely bullied, and their academic achievement suffers as a result of staying home. Bullied children may also suffer from serious illness, inability to focus, poor social relationships, and even have trouble holding down a job as adults.

Wolke’s study breaks new ground because it looks at children who were bullied, maltreated, or both. Other research has established that children having issues at home are at risk of being bullied or becoming bullies themselves, so the study’s findings that children who are both maltreated and bullied are at high risk for mental health problems is important information for policy makers, educators, and mental health providers.

“Self-harm — such as poisoning, cutting, and suicide attempts — can have both serious physical and mental consequences and ultimately lead to premature mortality,” Wolke said.

Public policy efforts and individual school systems have taken steps to prevent and address bullying. Nine U.S. states have policies or laws, often written into education codes, aimed at preventing bullying by defining prohibited behaviors, protecting oft-bullied groups (such as LGBT youth or youth with developmental disabilities), and outlining investigation and discipline processes.

The U.S. Substance Abuse and Mental Health Services Administration recently released a free mobile app, KnowBullying, that features conversation starting tips, warning signs, and strategies to empower caregivers and parents to talk to their children about bullying.

Still, Wolke fears these efforts do not go far enough to protect children from the mental health consequences he and other researchers routinely diagnose in bullied children.

Too often, he says, resources to protect children are aimed at addressing maltreatment by adults. But given his findings that bullying by peers actually does more long-term psychological damage, he hopes to see widespread governmental efforts that protect bullied children.

“Our studies found that bullying has more adverse effects on long-term mental health than maltreatment,” he said. “The U.N. convention on the Rights of the Child stipulated the protection of children from abuse and neglect. … But peer violence is not mentioned. Hence, this imbalance in governmental efforts requires attention.”

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