Objective: Compare rates of externalizing in children with autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD) symptoms to children with ADHD.
Method: Parents/caregivers of 85 children with ASD and/or ADHD were surveyed about their children's behaviours using the Autism Spectrum Disorders-Comorbidity for Children and the Autism Spectrum Disorders-Behaviour Problem for Children.
Results: Specific main effects analyses were then conducted. Children with ASD exhibited a higher number of externalizing (F(1, 83) = 83.34, p < 0.001) and tantrum behaviours (F(1,83) = 781.86, p < 0.001) than children without ASD.
Conclusions: ASD exacerbates the externalizing symptoms of ADHD during childhood. This study adds to the literature on the importance of assessing for a wide-range of possible behaviour problems in children presenting with ADHD symptomatology. The implications of these findings are discussed in the context of other research.