The impact of externalizing comorbidity on treatment outcome was examined in 104 youth ages 7-16 (M = 11.09 years) with autism spectrum disorder and primary anxiety/obsessive compulsive disorder who completed modular cognitive behavioral therapy (CBT) for anxiety/OCD. Three comorbidity profiles were utilized for group comparisons: participants with oppositional defiant or conduct disorder with attention-deficit hyperactivity disorder (ODD; CD; ADHD; group EXT, n = 25); those without ODD/CD and only ADHD (group ADHD, n = 46); and those without externalizing comorbidity (NO-EXT, n = 33). Post-treatment outcomes were measured continuously (Pediatric Anxiety Rating Scale, Clinical Global Impression-Severity) and categorically (treatment response, remission). The ADHD group was four times more likely of being a treatment responder compared to NO-EXT (OR 4.05). Comorbidity group did not impact remission. After controlling for pre-treatment scores, there was a significantly greater reduction of the CGI-S for ADHD versus NO-EXT and EXT versus NO-EXT, but results did not significantly differ for the PARS. Results suggest that a modular CBT approach yields positive impact for treatment outcomes in youth with comorbid externalizing problems, particularly among those with comorbid ADHD.
Keywords: Anxiety disorders; Autism spectrum disorder; Cognitive-behavioral therapy; Externalizing disorders; Obsessive–compulsive disorder.