Objective: This study examines the impact of comorbidity of attention-deficit/hyperactivity disorder (ADHD) with disruptive and anxiety disorders in childhood on clinical course and outcome. We consider the relative contribution of each comorbid symptom constellation, and also their interaction, to assess the following questions: (1) Does early comorbidity with conduct disorder (CD) and anxiety disorders define specific developmental trajectories?; (2) Is comorbid anxiety disorders in childhood continuous with anxiety disorders in adolescence?; (3) Does comorbid anxiety disorders mitigate the negative behavioral outcome of youth with ADHD?; and (4) Is there an interaction between comorbid CD and anxiety disorders, when they occur simultaneously, that predicts a different outcome than either comorbid condition alone?
Method: Thirty-two 15- to 18-year-old adolescent males, diagnosed with ADHD between 7 and 11 years of age, were re-evaluated for assessment of adolescent outcome 4.3–9.2 years later. Hierarchical regression analyses were run with each of the eight Child Behavior Checklist and Youth Self-Report problem scales, and the four anxiety symptom subscales of the Multidimensional Anxiety Scale for Children serving as outcome variables.
Results: Findings indicate that comorbid CD at baseline predicteds parent reports of behavior problems in adolescence, while comorbid anxiety disorders in childhood predicted youth reports of anxiety and social problems. Anxiety disorders without CD did not predict poor behavioral outcome. Children with both comorbid CD and anxiety disorder had the highest levels of parent-rated symptoms on follow up. In particular, adolescent social problems were best predicted by the combination of comorbid CD and anxiety disorder in childhood.
Conclusion: These data provide evidence that children with ADHD plus anxiety disorder do in fact have anxiety disorders, and that the combination of anxiety disorder and CD predicts a more rather than less severe course.