Utility of the Social and Communication Questionnaire in the Differentiation of Autism from ADHD

Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) often occur together. However, since symptoms of hyperactivity and inattention often occur in individuals with autism, distinguishing between the two conditions can be difficult. The purpose of this paper is to determine if the Social and Communication Questionnaire (SCQ), a commonly used screening measure for autism, can differentiate between the two conditions. Nineteen participants with ASD (17 males; mean age 10 years; SD 3.9) were compared with 57 participants with ADHD (43 males; mean age 8.4 years; SD 2.8); and 22 participants with ASD+ADHD (19 males; mean age 9.2 years; SD 2.8). Significant differences were found between the ASD and ADHD groups (13.43 versus 7.08, p < 0.0001) but not between the ASD and the mixed ASD+ADHD groups. A multinomial regression analysis identified the following nine questions as being especially important in differentiating between the ASD and ADHD groups: 6, 7, 13, 14, 26, 27, 33, 36 and 37. Implications of these findings are discussed.