Traumatic life events, polyvictimization, and externalizing symptoms in children with IDD and mental health problems

This study aims to examine the rates of potentially traumatic events (PTEs) and polyvictimization, as well as interrelationships among PTE types in children and youth with intellectual developmental disorder (IDD) and co-occurring mental health issues. It also examines the association between polyvictimization (experiencing three or more PTEs) and externalizing symptoms, controlling for IDD severity, sex and age.

The study utilized archival data collected from 2012 to 2020 by trained assessors (e.g., nurses, social workers, psychologists) at intake into clinical mental health services in the Province of Ontario, Canada. The sample included 502 children and youth (age range: 4-18 years) who were assessed using the interRAI Child and Youth Mental Health and Developmental Disability (ChYMH-DD) instrument. Using this standardized assessment, trained clinicians reported on children's demographics, traumatic life events, and externalizing symptoms (proactive and reactive aggression) among other physical and mental health indicators.

64.74 % of the children had experienced at least one type of PTE, whereas 33.06 % experienced lifetime polyvictimization. Most of the PTE types were positively correlated, with the strongest associations between physical, emotional abuse, witnessing domestic violence, and parental addiction. In a multivariate model, experiences of three or more PTEs (vs. none), mild or moderate IDD (vs. severe/profound), male sex (vs. female) were associated with greater externalizing symptoms. There was a quadratic relationship between age and externalizing symptoms.

The project advances knowledge on trauma and polyvictimization patterns and their association with IDD severity and externalizing symptoms in this population. Trauma-informed services should be tailored to the specific needs of these children.