Internalizing–Externalizing Comorbidity and Impaired Functioning in Children

Background: The comorbidity of mental illnesses is common in child and adolescent psychiatry. Children with internalizing–externalizing comorbidity often experience worse health outcomes compared to children with a single diagnosis. Greater knowledge of functioning among children with internalizing–externalizing comorbidity can help improve mental health care. Objective: The objective of this exploratory study was to examine whether internalizing–externalizing comorbidity was associated with impaired functioning in children currently receiving mental health services. Methods: The data came from a cross-sectional clinical sample of 100 children aged 4–17 with mental illness and their parents recruited from an academic pediatric hospital. The current mental illnesses in children were measured using the Mini International Neuropsychiatric Interview for Children and Adolescents (MINI-KID), and the level of functioning was measured using the World Health Organization Disability Assessment Schedule (WHODAS) 2.0. Linear regression was used to estimate the association between internalizing–externalizing comorbidity and level of functioning, adjusting for demographic, psychosocial, and geographic covariates. Results: Internalizing–externalizing comorbidity in children was associated with worse functioning compared to children with strictly internalizing comorbidities, β = 0.32 (p = 0.041). Among covariates, parent’s psychological distress, β = 0.01 (p = 0.004), and distance to the pediatric hospital, β = 0.38 (p = 0.049) were associated with worse functioning in children. Conclusions: Health professionals should be mindful that children with internalizing–externalizing comorbidity may experience worsening functioning that is disruptive to daily activities and should use this information when making decisions about care. Given the exploratory nature of this study, additional research with larger and more diverse samples of children is warranted.