The study, led by University of Warwick researchers, assessed a cohort of UK children (ALSPAC) from birth to fully understand the extent of bullying on psychosis in later life.
The analysis, in association with the University of Bristol, showed that victims, perpetrators and those who are both bullies and victims (bully-victims), are at an increased risk of developing psychotic experiences.
The term 'psychotic experiences' covers a range of experiences, from hearing voices and seeing things that are not there to paranoia.
Even when controlling for external factors such as family factors or pre-existing behaviour problems, the study found that not only those children who were bullied over a number of years (chronic victims), but also the bullies themselves in primary school were up to four and a half times more likely to have suffered from psychotic experiences by the age of 18.
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Those children who only experienced bullying for brief periods (eg at 8 or 10 years of age) were also at increased risk for psychotic experiences.
"These numbers show exactly how much childhood bullying can impact on psychosis in adult life. It strengthens on the evidence base that reducing bullying in childhood could substantially reduce mental health problems," Wolke said.
Wolke's team have previously looked at the impact of bullying on psychotic symptoms in 12 year olds, and there have been a range of short term studies that confirm the relation between being a victim of bullying and psychotic symptoms.