Associations between ADHD Symptoms and Psychiatric Symptoms in Children: Effects of Functional Impairment and...

ADHD is a highly prevalent neurodevelopmental disorder that is associated with elevated rates of co-occurring psychiatric symptoms. The present study evaluated the role of functional impairment in mediating the association between ADHD symptoms and psychiatric symptoms, as well as the moderating role of temperament traits.

Participants included two cohorts: an early childhood longitudinal sample (ages 2-4 years; n = 93) and a middle childhood cross-sectional sample (ages 7-11 years; n = 92). Both cohorts were oversampled for ADHD diagnosis or concerns. ADHD symptom severity, psychiatric symptoms, functional impairment, and temperament were assessed by caregiver report. Linear mediation and moderated mediation models were conducted, with ADHD symptom severity as the independent variable, functional impairment as the mediator, and psychiatric symptoms as the dependent variable; additionally, baseline psychiatric symptoms were covaried in the longitudinal early childhood analysis.

Across both samples, we found significant mediation effects for depression and aggression. In the middle childhood sample, functional impairment also fully mediated the association between ADHD and anxiety symptom severity. In the moderated mediation models, negative affect enhanced indirect effects on depression in early childhood and aggression in middle childhood. There were no protective effects of surgency.

Intervention specifically targeting functional impairment in this population has key clinical implications as it may help reduce the elevated risk of psychiatric comorbidity in the ADHD population, particularly in children with elevated levels of negative emotionality who are seemingly at highest risk.