School children who bully or are victims of bullying may face higher risks of anxiety, depression and other psychological disorders later in life, a new study finds.

The study, which followed more than 5,000 children in Finland, found that boys and girls who were frequently bullied were at greater risk than their peers of needing psychiatric treatment in their teens or early 20s.

The same was true of boys who were perpetrators of the bullying -- with the highest risks of mental health problems seen among boys who were both perpetrators and victims.

The findings, reported in the Archives of General Psychiatry, add to evidence that schoolyard bullying can have substantial psychological consequences -- and that, at least among boys, those who are both bullies and victims are the most troubled of all.

Parents and teachers should be aware that frequent school bullying should not be considered normal behavior, but has potentially serious consequences, lead researcher Dr. Andre Sourander, of the University of Turku in Finland, told Reuters Health in an email.

The study included 5,038 children who were followed from the age of 8 until age 24. At the outset, just over 6 percent of boys and almost 4 percent of girls were being frequently bullied, based on reports from the children, their parents and teachers.

Of boys, 6 percent routinely bullied other kids, while almost 3 percent were both bullies and victims. Among girls, less than one percent were either bullies or bully-victims.

The researchers used Finland's system of national registers to follow the study group's rate of psychiatric hospital admissions and prescriptions for antidepressants, anti-anxiety drugs and anti- psychotics.

Overall, one-third of boys who had been both bullies and victims ended up taking a psychiatric medication at some point between the ages of 13 and 24, while 17 percent were admitted to a psychiatric hospital. That compared with rates of 12 percent and 5 percent, respectively, among boys who had not been involved in bullying.

Among girls, 32 percent of those who had been frequently bullied were eventually prescribed a psychiatric medication, compared with 16 percent of girls who had not been bullied. Meanwhile, 12 percent of victims were hospitalized for psychiatric treatment, versus 4 percent of other girls.

When the researchers considered the children's emotional health and behavior at the start of the study, only boys who were already showing problems were at increased risk of later psychiatric conditions.

But with girls, those who were bullied were at heightened risk of later problems even if they initially showed no emotional or behavioral difficulties.

It's not clear why this gender difference exists, according to Sourander's team, but it's possible that different forms of bullying have different long-term effects, they note. With boys, bullying is often overt and physical, while for girls, it is more likely to come in the subtle form of teasing, gossip and exclusion.

One of the main messages from the findings, Sourander noted, is that schools need to keep bullying incidents from escalating.

The education systems are of central importance (in) early detection, he said. Failure of the school system to take preventive action should be considered a failure to discharge the school authority's duty of care.

SOURCE: Archives of General Psychiatry, September 2009.