Prevalence and outcomes of childhood trauma in people with intellectual disability and borderline intellectual functioning: findings from a prospective UK population-based cohort study.

BACKGROUND: There have been limited studies investigating psychiatric outcomes of childhood trauma in individuals with intellectual disability or borderline intellectual functioning. AIMS: To investigate the associations of (a) intellectual disability or borderline intellectual functioning with childhood trauma up to age 11 years; and (b) childhood trauma with psychiatric diagnostic, prescribing and behavioural outcomes in adolescence and early adulthood among individuals with intellectual disability or borderline intellectual functioning. METHOD: This was a prospective cohort study using data from the Avon Longitudinal Study of Parents and Children birth cohort with linked primary care data. RESULTS: Of 8661 participants, 310 had intellectual disability or borderline intellectual functioning and 107 had intellectual disability. We found increased odds of bullying (odds ratio = 1.84, 95% CI: 1.39-2.43) and sexual abuse (odds ratio = 2.11, 95% CI: 1.09-4.11) among individuals with intellectual disability or borderline intellectual functioning compared with those without. In the group with intellectual disability, the odds of bullying were attenuated (odds ratio = 1.66, 95% CI: 0.97-2.86), and estimates for sexual abuse were imprecise (odds ratio = 0.69, 95% CI: 0.09-5.09). Among those with intellectual disability or borderline intellectual functioning, we found increased odds of challenging behaviour (odds ratio = 2.62, 95% CI: 1.05-6.57), psychotropic prescribing (odds ratio = 2.73, 95% CI: 1.55-4.81), and suicidal and self-harm behaviours (odds ratio = 3.42, 95% CI: 1.15-10.20) in individuals who had experienced bullying, and increased odds of challenging behaviour (odds ratio = 3.31, 95% CI: 1.28-8.53) in individuals who had experienced emotional abuse compared with those who had experienced no trauma. CONCLUSIONS: We provide evidence of increased odds of childhood bullying and sexual abuse among those with intellectual disability or borderline intellectual functioning. In this group, bullying is associated with increased odds of challenging behaviour, psychotropic prescribing, and suicidal and self-harm behaviours.