Not all adverse childhood experiences were linked to the same pattern of psychotic-like experiences in a large UK birth-cohort study. Bullying was associated with experiences that remained persistently high or increased from adolescence into early adulthood, while childhood maltreatment was associated with an increasing pattern over time.
Psychotic-like experiences can include hearing voices or holding unusual beliefs. Most are transient, but around 20% persist across follow-up periods of up to eight years. Persistent experiences are associated with a greater risk of psychosis and other mental health disorders.
What the study examined
Hudson and colleagues used data from 4,448 participants in the Avon Longitudinal Study of Parents and Children, a UK birth cohort. Participants provided information about psychotic-like experiences at one or more of ages 12, 18 and 24.
The experiences were assessed through semi-structured interviews and rated as suspected or definite. The researchers examined six types of adverse childhood experience occurring before age 12: bullying, childhood maltreatment, parental mental health problems, parental substance abuse, parental separation and parental intimate partner violence.
The analysis also accounted for socioeconomic status, genetic susceptibility and exposure to other adverse experiences. Because this was an observational study, these adjustments cannot establish that any one experience caused later psychotic-like experiences.
Three patterns over time
The researchers identified three trajectory groups. About 93% of participants were in a low group, reporting consistently low levels from ages 12 to 24. Around 2.5% were in a high group, with persistently high levels. About 5% were in an increasing group, reporting few experiences at age 12 and more as they grew older.
Participants in the high or increasing groups were more likely to have experienced adverse childhood experiences than those in the low group. After accounting for potential confounders and other adverse experiences, bullying and childhood maltreatment showed the clearest associations.
- Childhood maltreatment was associated with a relative risk ratio of 1.47 for belonging to the increasing group rather than the low group. The 95% confidence interval was 1.03 to 2.10.
- Bullying was associated with a relative risk ratio of 1.83 for belonging to the increasing group rather than the low group. The 95% confidence interval was 1.26 to 2.66.
- Bullying was associated with a relative risk ratio of 1.78 for belonging to the high group rather than the low group. The 95% confidence interval was 1.07 to 2.93.
Other types of adverse childhood experience were not significantly associated with the psychotic-like experience trajectories after the adjustments. The findings largely remained after the researchers accounted for individual genetic risk for schizophrenia and depression.
Why the findings need careful interpretation
The study suggests that bullying may be associated with both persistent and increasing psychotic-like experiences, while childhood maltreatment may be associated with experiences that increase over time. It does not show that bullying or maltreatment directly causes these outcomes.
The researchers noted that the final sample represented 28% of the original cohort. Participants with missing data were more likely to have experienced childhood maltreatment and parental intimate partner violence. Drop-out was also linked to lower socioeconomic status, which may have left a sample weighted toward people with higher socioeconomic status.
Not everyone provided information at all three timepoints, so some participants may have been placed in the wrong trajectory group. When the analysis was restricted to participants with complete data, the association between bullying and the high group was no longer statistically significant. The cohort included only white participants, limiting how widely the findings can be applied.
The researchers also reported that trajectory assignment was not a perfect fit for all participants. The confidence interval for childhood maltreatment and the increasing group was relatively wide, with its lower end close to 1. Residual confounding also cannot be ruled out.
What comes next
The findings support closer study of interpersonal adversity, including bullying and maltreatment, in research on young people’s mental health. Anti-bullying interventions can reduce bullying, but it is not yet known whether they prevent persistent psychotic-like experiences specifically.
The authors called for studies involving more ethnically diverse participants and a broader range of socioeconomic backgrounds. They also highlighted the need to examine the severity, timing and duration of adverse experiences, follow participants beyond age 24 and test whether interventions can reduce persistent psychotic-like experiences.
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