Objectives: This study investigates the extent to which problems with Theory of Mind also occur in children with ADHD. ToM in ASD and ADHD is additionally compared with ToM in typically developing children of the same age. In addition, we investigate if response inhibition, working memory and language comprehension serve as mechanisms in understanding ToM problems in children with ASD and ADHD.
Methods: Semi-structured clinical interviews for ASD and ADHD were carried out to confirm diagnosis: ADOS, ADI-R, and PICS. ToM was tested with two “false belief” tasks in children with ASD (n=41), children with ADHD (n=37), and a healthy control group (n=38). Two executive functioning tasks, i.e. a working memory and a response inhibition task, and a language comprehension task were administered to determine if these are possible mechanisms underlying problems with ToM.
Results: Children with ASD and children with ADHD scored similarly low on the ToM tasks. However, the lower scores on ToM in ADHD were partly accounted for by working memory, variability in performance and language comprehension. In contrast, the problems in ToM in ASD persisted if working memory, variability in performance and language comprehension were taken into account. Response inhibition did not mediate ToM performance.
Conclusions: Children with ADHD have problems with ToM, just like children with ASD. However, the mechanisms underlying these ToM problems seem to be different in children with ADHD than in children with ASD. Our findings fit in a growing literature that shows that children with ADHD have social problems, including ToM problems. Even if the mechanisms contributing to social problems in ADHD differ from those in ASD, clinicians need to be aware of and monitor the social problems that are present in this group. ToM problems in ASD cannot be explained by more general EF and language comprehension skills.