Prospective study of peer victimization in childhood and psychotic symptoms in a nonclinical population at age 12 years.

CONTEXT Psychotic symptoms are commonly experienced in nonclinical populations of adolescents and adults and have been shown to be predictive of later schizophreniform disorders. Associations between adverse experiences in childhood and psychotic symptoms in adulthood have been demonstrated. OBJECTIVE To examine whether peer victimization is associated with psychotic symptoms in a population-based sample of 12-year-olds. DESIGN Prospective cohort study. SETTING Assessment clinic for 12-year-old members of the Avon Longitudinal Study of Parents and Children birth cohort in Bristol, England, where parents had participated since pregnancy and their children completed a range of physical and psychological annual assessments since age 7 years. PARTICIPANTS A total of 6437 respondents with complete interviews (mean age, 12.9 years). MAIN OUTCOME MEASURE The Psychosis-like Symptoms Interview developed for the study using stem questions, glossary definitions, and rating rules, adapted from the National Institute of Mental Health Diagnostic Interview Schedule for Children-IV and the Schedules for Clinical Assessment in Neuropsychiatry. The interview, carried out by trained psychology graduates, investigated respondents' experience of psychotic symptoms (hallucinations, delusions, and thought disorders) over the previous 6 months. RESULTS The risk of psychotic symptoms was increased about 2-fold (odds ratio = 1.94; 95% confidence interval, 1.54-2.44) among victims of bullying at ages 8 and/or 10 years, independent of other prior psychopathology, family adversity, or child's IQ. Similar results were found using mother and teacher reports of victimization. Associations were stronger (up to odds ratio = 4.60; 95% confidence interval, 3.24-6.50) when victimization was chronic or severe (ie, experience of relational as well as overt victimization reported). CONCLUSIONS Peer victimization in childhood, especially if it is chronic or severe, is associated with psychotic symptoms in early adolescence. These results lend further support to the relevance of psychosocial factors in the etiology of psychotic symptoms in nonclinical populations, which may increase the risk of adult-onset psychotic disorders.