Correlates of comorbid psychopathology in children with ADHD.

Objective: To investigate correlates of internalizing and externalizing psychopathology in a clinical sample of children with attention-deficit/hyperactivity disorder (ADHD).

Methods: Parent and teacher Child Behavior Checklists were administered to 300 children with ADHD to ascertain comorbid symptoms. Based on previous research, a seven-step hierarchical regression analysis was developed. Six hierarchical regression analyses were conducted with either parent or teacher Child Behavior Checklist aggression, delinquency, or anxious/depressive comorbid symptoms as dependent measures.

Results: Controlling for (1) variables known to increase risk for ADHD child psychopathology and (2) estimated duration of ADHD, our results suggest that the presence of comorbid symptoms is influenced by age of onset. An early age of onset of ADHD was correlated with a greater rate of parent-reported child aggressive symptoms, and a later age of onset was correlated with a greater rate of parent-reported child anxious/depressive symptoms. Elevated levels of comorbid externalizing and internalizing symptoms are associated with greater ADHD symptom severity.

Conclusions: Comorbid externalizing and internalizing symptoms are correlated with age of ADHD onset and are related to the severity of clinical presentation in a referred sample of children with ADHD.