Effects of Adverse Childhood Experiences on Severe Mental Health Conditions in Early Adulthood: A Twin Study
Year: 2026
Type: preprint
Study design: Observational Study
Abstract: Importance Adverse childhood experiences are associated with later severe mental health conditions, but the extent to which these associations reflect a causal effect of adversity rather than confounding remains unclear. Objective To test whether within-twin-pair differences in reported adverse childhood experiences predict differences in severe mental health conditions in early adulthood, and to decompose covariation between adverse childhood experiences and severe mental health conditions into genetic and environmental components.Design Setting and Participants This study used data from the Twins Early Development Study, a population-based cohort of twins born in England and Wales (1994-1996), with assessments at ages 12, 14, 16, 21, and 26. Within-twin-pair regression and bivariate biometric twin models were used to distinguish potential causal effects from familial confounding.Exposures Childhood maltreatment (abuse and neglect, retrospective, ages 21 and 26) and peer victimization (bullying, prospective, ages 12, 14, 16).Main Outcomes and Measures Seventeen measures of severe mental health conditions spanning psychosis-spectrum symptoms, (hypo)manic symptoms, self-harm and suicidal behaviour, and reported diagnoses.Results Outcomes were assessed at ages 21 (13,794 individuals) and 26 (11,436 individuals). After false discovery rate correction, childhood maltreatment was associated with all 17 outcomes at the population level and peer victimization with 16. Monozygotic within-pair models were estimable for 14 outcomes. All 14 maltreatment associations remained significant, with pooled symptom estimates attenuating by 21% (0.30 to 0.24) and pooled odds ratios of 1.85 vs 1.95 at the population level. Only 2 peer victimization associations remained (paranoia and hallucinations at age 21), with attenuation of 53% (0.20 to 0.09) and pooled odds ratios of 1.18 vs 1.59. Bivariate biometric twin models supported the within-pair findings while also demonstrating that all covariances were partially attributable to shared genetic liability.Conclusions and Relevance Associations between adverse childhood experiences and severe mental health conditions in young adulthood reflected both shared genetic liability and potential causal effects. Childhood maltreatment showed more persistent within-pair associations than peer victimization, consistent with a greater contribution of non-shared environmental effects. Findings highlight childhood maltreatment as a potentially modifiable pathway to severe psychopathology, supporting the importance of trauma-informed care.
Language: English
Topic: Child Abuse and Trauma
Subfield: Clinical Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
OpenAlex ID: W7204174138