Frequent exposure to bullying by peers during childhood increased the risk of deliberate self harm among young adolescents aged 12 years. We documented that this association was present at the beginning of adolescence, was similar for reports of bullying by mothers and accounts of bullying by children, and was independent of potential confounding selection effects of maltreatment by an adult, family environmental risk factors, early behavioural and emotional problems, and low IQ. We also showed that bullied children who self harmed differed from their bullied counterparts who did not self harm in having a family history of suicidal behaviour, being physically maltreated by an adult, and having co-occurring mental health problems (conduct disorder, borderline personality characteristics, depressive or psychotic symptoms).
