Differential effects of childhood maltreatment types and timing on psychopathology in formerly out-of-home placed young adults

Childhood maltreatment (CM) increases the risk of psychopathology. Besides CM types and severity, the timing of exposure is an important modulating factor in this association, as childhood and adolescence comprise sensitive developmental periods for brain maturation and socio-emotional development. Nevertheless, previously reported associations between the severity of subtypes and timing of CM and psychopathology have been heterogeneous and have hardly considered vulnerable groups broadly exposed to CM, such as out-of-home-placed youth. Thus, we investigated the association between CM types and timing and psychopathology in a sample of formerly out-of-home placed young adults (N = 185; 32% women, age mean = 26.38, SD = 3.49 years). CM was assessed using the Maltreatment of Abuse Chronology of Exposure Scale and general, internalizing and, externalizing problems were assessed using the Achenbach System of Empirically Based Assessment. We employed conditional random forest regression to estimate the importance of CM types (abuse, neglect, peer victimization, and sexual abuse), timings (ages 3–18) as well as CM severity, multiplicity, and duration on adult general, internalizing, and externalizing problems. We validated the results using diagnoses of mental disorders assessed in clinical interviews, which were classified under general, internalizing, and externalizing clusters based on the Hierarchical Taxonomy of Psychopathology model. We found that CM severity and multiplicity were stronger predictors of internalizing problems than timing-specific effects of CM types. Abuse in early childhood and peer violence in late adolescence were stronger predictors of externalizing problems compared to global CM measures. Our findings highlight the importance of considering CM type and timing when testing CM-associated risks for psychopathology. This might further be valuable in therapeutic settings to guide maltreatment-informed interventions. Reducing violent caregiving environments in early childhood and preventing peer victimization in adolescence may be especially important in counteracting CM-associated risks of externalizing behaviors.