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.
Bullying and victimization are both associated with poor family functioning, parental violence, subsequent conduct and personality disorders, and criminality, and bullying and victimization behaviors are stable between the ages of 8 and 16 years.
Some Finnish study highlights:
• Adult psychiatric morbidity was assessed 3 times between ages 18 and 23 years as part of the military call-up examination.
• Military service is mandatory in Finland; it starts after age 18 years and lasts 6 to 12 months for all Finnish men.
• Subjects were classified into 1 of 5 groups of disorders: "anxiety disorder," "depressive disorder," "antisocial personality disorder," "substance abuse disorder," and "psychotic disorder."
• Boys who were both bullies and victims who screened positive had a 5-fold increased risk for a psychiatric disorder as against those who screened negative and who were not involved in bullying.
• Children with frequent bullying or victimization (11%) who screened positive accounted for 28% of adult psychiatric diagnoses.
• The authors concluded that combined bullying and victimization posed the greatest risk for psychiatric morbidity followed by bullying and victimization. The authors recommended a screening strategy to identify bullies, victims, and combined bullies and victims followed by psychiatric screening as more cost-effective than universal screening to identify future psychiatric disorders.
"Both bullying and victimization during early school years are public health signs that identify boys who are at risk of suffering psychiatric disorders in early adulthood," the authors write. "The school health and educational system has a central role to play in detecting these boys at risk."
The study was confined to boys only.