Symptom similarities and differences in social interaction between autistic children and adolescents with and without ADHD

Autism Spectrum Disorder (ASD) and Attention Deficit Hyperactivity Disorder (ADHD) are two often co-occurring neurodevelopmental conditions. Nevertheless, there is limited research about symptom differences between ASD and ASD + ADHD groups. This study examined differences in social interaction and communication between children and adolescents with ASD and with ASD + ADHD. A total of 112 participants were identified from two clinical trials. Fifty-six children and adolescents with ASD aged 8-17 years were matched for age, gender and general intelligence quotient with fifty-six children and adolescents with ASD + ADHD. Group differences in scores on the Autism Diagnostic Observation Schedule were analysed. Our results showed that participants with ASD and with ASD + ADHD had similar profiles of social communication interaction challenges and restricted behaviour. However, items assessing gestures: Conventional, Instrumental or Informational Gestures and Empathic or Emotional gestures showed significant differences between the groups suggesting that the ASD + ADHD group used descriptive gestures to communicate to a greater extent than the ASD group. These findings suggest that children and adolescents in both groups have similar difficulties in social communication and interaction with observed differences in the use of gestures. Possible reasons and implications for the differences in the use of gestures are discussed.