Though a substantial body of research has found an association between being bullied in childhood and adolescence and the later development of psychosis, a new study sought to overcome several previous limitations, including the need for prospective data and better controlling for confounding factors.
In the study, to appear in the journal Psychological Medicine next month, researchers at the University of Otago in Christchurch, New Zealand, used data from a 35-year longitudinal birth cohort study to examine links between bullying victimization between the ages of 13 and 16 years and psychotic symptoms between the ages of 18 and 35 years.
The researchers also sought to explore the possibility that associations could be due to confounding variables, so they controlled for gender at birth, childhood socioeconomic status and intelligence quotient, sexual abuse history, certain measures of behavior and attention problems in childhood, and psychotic symptoms in adolescence. These factors were selected because they were used in previous research on the topic and because they have been shown to be connected to bullying victimization and symptoms of psychosis.
The 1265 participants were born in 1977 and followed until they were 35 years old. They “were assessed at annual intervals from birth to age 16 years, then at ages 18, 21, 25, 30 and 35 years, using a combination of semi-structured interviews, standardized testing and teacher questionnaires,” the authors wrote.
During participants’ younger teen years, they and their parents answered questions about bullying victimization and other aspects of the school and social experience. At each assessment during adulthood, participants underwent comprehensive testing to assess mental health and psychological adjustment, including the presence of any psychotic symptoms such as hallucinations, delusions, and paranoia.
The final sample with complete data consisted of 1018 individuals from the original cohort. After repeated analyses and controlling for covariation, results show that rates of psychotic symptoms were 21% higher among participants who had the most exposure to bullying vs those with no exposure. The findings further suggest that the link was mostly explained by childhood behavior problems and, to a lesser extent, sexual abuse and psychotic symptoms in childhood.
These results align with previous research suggesting a connection between childhood abuse and subsequent psychotic symptoms, as well as studies showing that associations between bullying and psychosis are not likely causal “but instead reflect a continuity of disordered behavior across childhood in adolescence, and the fact that individuals who display such behavior are more likely to become the targets of bullies,” according to the authors.
Despite the suggested lack of causality, clinicians should be aware that bullying exposure remains a risk marker for later symptoms of psychosis, and it increases the risk of suicidal behavior and social maladjustment. “Identification of children who may be at greater risk of bullying due to their individual and behavioral issues may help to relieve other adverse psychosocial outcomes that stem from bullying victimization,” they concluded.
Boden JM, van Stockum S, Horwood LJ, Fergusson DM. Bullying victimization in adolescence and psychotic symptomatology in adulthood: evidence from a 35-year study. Psychol Med. 2016; 46(6):1311-20.