Irish scientists have found a direct link between childhood trauma, such as bullying, and psychotic experiences.

According to a study by scientists at the Royal College of Surgeons in Ireland (RCSI), this marks the first time such a link has been found. Furthermore, they have also found that the cessation of traumatic experiences is ‘associated with a significant reduction in the incidence of psychotic experiences', such as hearing voices.

The scientists set out to determine whether childhood traumas, such as a physical assault or bullying, could be considered a cause of psychotic experiences. They looked at over 1,100 teenagers aged between 13 and 16 and assessed them for childhood trauma and psychotic experiences at the start of the study, and again three and 12 months later.

"Our findings showed a clear relationship between exposure to childhood trauma and the onset of psychotic symptoms because the strength of the relationships was large in terms of odds ratios. We also saw a dose-response relationship with the odds of psychotic symptoms increasing in line with increasing levels of bullying," explained senior investigator, Prof Mary Cannon, of the RCSI and Health Research Board (HRB).

However, the study also showed for the first time that cessation of traumatic experiences ‘predicted a significantly reduced incidence of psychotic experiences compared to individuals for whom the traumatic experiences continued'.

"This is a very encouraging finding and suggests that population-based approaches could have a large impact reducing the prevalence of psychotic symptoms," commented lead investigator, Dr Ian Kelleher, of the RCSI.

The study noted that the largest group found to be inflicting physical harm on children was their classmates.

"These findings place new weight on calls for more comprehensive preventions and intervention strategies against childhood trauma in the community from abuse at home and bullying in schools...As most bullying takes place within the school, teacher training could have a very important role to play in reducing this harm," the scientists added.

Details of these findings are published in the American Journal of Psychiatry and were presented at the European Society for Child and Adolescent Psychiatry Congress, which took place in Dublin this week.