Significantly while victims of bullying were more likely to develop only anxiety disorders, the bullies themselves could develop antisocial personality disorder.

And those who have both been bullies and bullied tended to develop both anxiety and antisocial personality disorder, the team from Turku University in Finland said in the journal Pediatrics.

Andre Sourander, the lead researcher, noted that information about the long-term effects of bullying had considerable public health significance that would justify universal or targeted preventive interventions and research directed at school bullying.

They examined 2540 boys born in 1981. At the age of 8 years, these boys were asked whether and how often they bullied other children, were targets of bullying, or both. Parents and teachers also answered questions about bullying or victimisation. This information was then compared with psychiatric diagnoses in young adulthood - made during medical exams for compulsory military service and army registry at 18 to 23 years of age.

Bullying is defined as an aggressive act that can be physical, verbal, or indirect, with an imbalance of power in which the victim cannot defend himself and the behavior is repetitive.

In a US survey, 17% of children in grades 6 to 10 reported being bullied, 19% being bullies, and 6% being both bullies and victims.