A community-based study of more than 4700 participants from the United Kingdom showed that those who were bullied at the age of 10 years were more than twice as likely to suffer from episodes of psychosis by the age of 18 as those who were never bullied.
Interestingly, children who reported doing the bullying themselves were almost 5 times more likely to have psychotic experiences by the age of 18 years.
"But we were surprised that we found an increased risk for the bullies," added Dr. Wolke.
He noted that the results show that bullying can have a significant impact on adult life and that clinicians should routinely ask their child patients about peer bullying experiences.
"It strengthens the evidence base that reducing bullying in childhood could substantially reduce mental health problems. The benefit to society would be huge, but of course the greatest benefit would be to the individual," he said in a release.
The study was published December 17 in Psychological Medicine.
As reported at the time by Medscape Medical News, Dr. Wolke and his investigative team published a study in the Archives of General Psychiatry in 2009 showing that children who were bullied at the ages of 8 or 10 years were twice as likely to develop psychosis in early adolescence. And if the victimization was characterized as chronic or severe, the risk increased nearly 4-fold.
Dr. Dieter Wolke
To investigate the long-term effect of childhood bullying, the investigators followed up with 4720 of the offspring (56.5% girls, 95.7% white) from the prospective Avon Longitudinal Study of Parents and Children (ALSPAC).
In the original ALSPAC study, 14,541 pregnant women with a delivery date between April 1991 and December 1992 were enrolled and filled out mailed questionnaires, sent periodically, about their offspring's health and development.
Beginning at the age of 7 years, their children underwent yearly in-person interviews and psychological and physical tests. When they were 8 and 10 years of age, the children were also asked questions from the Bullying and Friendship Interview Schedule. Mothers' reports about their offsprings' bullying experiences were assessed with the Strengths and Difficulties Questionnaire.
For the current analysis, the researchers also examined results of the psychosislike symptoms semistructured interview to assess possible psychotic experiences by the age of 18 years.
Psychotic experiences were defined as visual or auditory hallucinations, delusions, and/or thought interference.
"Not a Rite of Passage"
Results showed that 32.2% of the participants had been victims of bullying at the age of 8, 5.9% had been bully/victims, and 1.1% had been perpetrators of bullying, according to child reports. These numbers dropped to 18.6%, 4.3%, and 0.8%, respectively, at the age of 10 years.
A significantly higher prevalence of psychotic experiences by the age of 18 years was found for those who had been victims of childhood bullying, according to both child reports at the age of 10 years (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.6 - 3.4) and mother reports (OR, 1.6; 95% CI, 1.1 - 2.3), than for those who had never been bullied ― even after controlling for a number of factors, including child's sex, intelligence, and adolescent behavioral/emotional problems and depression symptoms.
The ORs for psychotic experiences as adults were even higher for those who were bullies/victims at the age of 10 years (3.1; 95% CI, 1.7 - 5.8 and 2.9; 95% CI, 1.7 - 5.0 for child and mother reports, respectively).
Those who were childhood bullies had the highest ORs for later psychotic experiences, based on child reports (4.9; 95% CI, 1.3 - 17.7) but not on mother reports (1.2; 95% CI, 0.46 - 3.1).
"We want to eradicate the myth that bullying at a young age could be viewed as a harmless rite of passage that everyone goes through. It casts a long shadow over a person's life and can have serious consequences for mental health," said Dr. Wolke.
"The results show that interventions…should start early, in primary school, to prevent long-term, serious effects," he added. "This clearly isn't something that can wait until secondary school to be resolved; the damage may already have been done."
He reported that the investigators plan to continue following up with the ALSPAC cohort and are currently working on funding applications to continue to see the participants when they are 23 and 24 years of age.