Dan Olweus (32) was the first to examine the lasting
effects of bullying, demonstrating that young male victims were more depressed and had lower self-esteem in early adulthood than their nonbullied peers. Twenty years later, our study, using data from a large prospective British birth cohort, shows that being bullied in childhood retains associations with poor mental, physical, and cognitive health outcomes at least to middle adulthood, 40 years after exposure. The effects were small but similar to those of other forms of childhood hardship, and the effects remained significant after adjusting for established correlates of bullying victimization, including both internalizing and externalizing problems in childhood and exposure to other forms of early adversity. In addition, we observed that bullying victimization was also associated with poor social relationships, economic difficulties, and lower perceived quality of life in the middle adult years. Forty years after exposure, individuals who had been bullied in childhood continued to show persistent and pervasive negative sequelae.
Three findings deserve particular mention. First, estimates of the associations between bullying victimization and adult outcomes were small but robust to adjustment for a number of key confounders. The strength of the associations we observed—with most odds ratios in the region of 1.5—likely reflects the four decades that separated exposure to bullying and the assessments of later outcomes. The findings are compelling in showing that the independent contribution of bullying victimization survives the tests of time and confounding. It is unlikely, of course, that bullying operates in isolation to create such lifelong adversities. Future studies should examine bullying victimization in the context of other forms of childhood abuse and identify pathways leading to poor adult outcomes.
Second, the longitudinal associations between bullying victimization and adult outcomes were similar to those of placement in public or substitute care or exposure to multiple adversities within the family. The long-term effects of these forms of childhood adversity have been extensively documented (33). Our findings suggest that bullying leaves similar long-term traces that are still evident well into the adult years.
Third, the impact of bullying victimization is pervasive, affecting many spheres of a victim’s life. This study is among the first to show that being bullied in childhood influences not only victims’ mental health but also social and economic outcomes. Findings from the Great Smoky Mountains Study demonstrated that childhood bullying victimization was associated with variations in health, wealth, and social relationships at age 25 (34). In addition, our findings indicate that bullying also influenced later cognitive functioning, over and above controls for childhood IQ. The mechanisms underlying this association remain to be clarified. On the one hand, it could mirror links between maltreatment and cognitive problems observed in other studies in childhood (35). On the other, it is possible that bullying victimization contributes to early aging, as found in research on telomere shortening that is contingent on other forms of abuse (36, 37). Interestingly, like Copeland et al. (13), we found that bullying victimization was not associated with increased risks of adult alcohol dependence in the National Child Development Study cohort. Developmental pathways to alcohol problems start in the teenage years, and often involve peer influences, something that young victims of bullying may be less exposed to given their difficulties with peers.
The developmental mechanisms that translate childhood bullying victimization into poor mental, physical, and cognitive health in adulthood remain unclear. One possibility is that poor mental health outcomes are a function of symptoms that developed closer in time to bullying exposure. Untreated signs of distress appearing early in life may be early precursors to a life marked by symptoms of anxiety and depression. A second possibility is that bullying victimization generates further abuse from peers or adults, forming the first stage in a cycle of victimization that perpetuates itself over time and across situations. Past studies have shown that children exposed to violence are at increased risk of revictimization of this kind and also of being subjected to differing types of violence (38, 39). Finally, in line with hypotheses derived from theories of the biological embedding of stress (40), previous studies have shown that bullying victimization in childhood is associated with a blunted cortisol response (41) and higher serotonin transporter gene methylation levels (42). Effects of this kind could constitute further pathways for the persistence of poor outcomes across the life course.
Our findings should be interpreted in light of several limitations. First, parents were not shown a definition of bullying, nor were they instructed to consider a particular reporting period. The prevalence of bullying and its associations with childhood correlates were, however, similar to those reported today, suggesting that understandings of the concept have not changed greatly over the years. Second, the National Child Development Study did not include questions about participants’ own acts of bullying. As a result, we were unable to identify children who were both victims and perpetrators. Past studies suggest that the associations we observed are partly driven by this group (13). Third, attrition in the National Child Development Study across five decades of assessment was not negligible, although it is unlikely that this affected the pattern of our findings; dropout was not associated with bullying victimization (see Table S1 in the online data supplement) and we controlled for other effects of selective attrition by including weights throughout the analyses. Fourth, depression and anxiety disorders assessed in the National Child Development Study were limited to the previous week. This is reflected by the relatively low prevalence rates of those disorders. Therefore, our study fails to capture an unknown proportion of cases with a psychiatric disorder. However, the impact of this on our findings would likely be to underestimate the associations between childhood victimization and psychiatric problems in midlife. As a result, the conclusions we report are probably a conservative estimate of the true associations between childhood bullying victimization and psychopathology in midlife. Fifth, although we controlled for a wide range of potential confounders, it remains possible that there are other factors not assessed in the National Child Development Study that could explain why young victims of bullying face poor health outcomes in later life. These unmeasured factors limit causal inferences relating to childhood bullying victimization. We examined other potential confounders, including physical disabilities, number of people in the household, birth order, family difficulties, and quarrels with siblings, but did not include these variables in further tests as they did not remain significantly associated with adult outcomes in multivariate analyses.
Like other forms of childhood abuse, bullying victimization has a pervasive effect on functioning and health outcomes up to midlife. In addition to reducing bullying behaviors in the early years, our findings suggest that intervention efforts should aim to minimize poor health outcomes in young victims of bullying. Not only may this stop children’s suffering, it may also help prevent problems persisting to adolescence and adult life. Our findings also emphasize the importance of gaining a better understanding of the mechanisms underlying the persistence and pervasiveness of the impact of childhood bullying victimization. These risk mechanisms could become suitable targets for intervention programs designed to reverse the effects of early life adversity later in the life course. Future research elucidating the biological, behavioral, or social pathways from childhood bullying victimization to poor adult outcomes could help the development of effective intervention strategies to reverse the effects incurred by young victims of bullying and possibly modify the course of their long-term trajectories.