Being bullied in childhood doubles a young person’s likelihood of having psychotic symptoms in early adolescence, UK researchers report.

In fact, with longer-lasting and more severe bullying comes greater risk, Dr. Andrea Schreier of Warwick Medical School in Coventry, England and her colleagues found.

“Chronic or severe peer victimization has non-trivial, adverse, long-term consequences,” they write in the Archives of General Psychiatry. “Reduction of peer victimization and the resulting stress caused to victims could be a worthwhile target for prevention and early intervention efforts for common mental health problems and psychosis.”

Both kids and adults “commonly” have psychosis-like symptoms or experiences, without full-blown mental illness, Schreier and her team explain. Young children who have these symptoms are more likely to develop schizophrenia and similar types of mental illness as young adults, the researchers add, while trauma in childhood also has been tied to adult psychosis risk.

To investigate whether there might be a direct link between trauma from bullying and psychosis symptoms, the researchers looked at 6,437 12-year-olds participating in a long-term study of children and their parents. All of the children had been completing annual psychological and physical health assessments since they were seven years old.

In the current report, the researchers determined whether the 12-year-olds had any of 12 different psychotic symptoms, such as visual or auditory hallucinations, delusions of being spied on, or beliefs that they could broadcast their thoughts to others. Children had also been surveyed about peer victimization at 8 and 10 years of age.

Nearly 14 percent of the children had definite or suspected psychotic symptoms, although these included symptoms that occurred when the children were going to sleep or waking up, feverish, or under the influence of substances; 11.5 percent had intermediate symptoms, meaning they had at least one suspected or definite symptom that wasn’t related to sleep, fever or drugs; and 5.6 percent had at least one definite symptom of psychosis.

Overall, 46 percent of the children reported having experienced victimization - including either direct bullying or “relational” victimization such as being excluded - at age 8 or 10, while 54 percent weren’t victimized at either age.

Kids who reported being bullied at either age were roughly twice as likely as the other children to have psychotic symptoms, regardless of any other mental health problems, family situation, or IQ.

When children experienced bullying at both ages, or bullying was severe (meaning it was both overt and relational), their risk of having psychotic symptoms was increased up to 4.6-fold.

While children who get bullied are often less assertive and more easily upset than their peers who aren’t victimized, the researchers note, the fact that the findings showed a “dose-response” relationship between bullying and psychotic symptoms - meaning the greater the severity of bullying, the stronger the link - suggests that bullying actually helped cause children’s psychotic symptoms, rather than vice-versa.

Future research is needed, they conclude, to understand whether victimization changes how children process thoughts and emotions or alters stress response, or whether psychotic symptoms have genetic roots.

SOURCE: Archives of General Psychiatry, May 2009.