The overlap between Attention-deficit/hyperactivity disorder and Autism Spectrum Disorder symptoms and their association with reading skills and social cognition ability

ADHD and ASD are both associated with social cognition and literacy deficits in childhood. Although ADHD and ASD are highly comorbid conditions, few studies have sought to examine to the role that co-occurring diagnoses has on these important life skills. This thesis aimed to address this lack of research by first investigating the effect of ASD traits on reading comprehension performance in a large scale sample of children with ADHD, together with an examination of the full profile of literacy ability in ADHD. Results revealed that basic reading was an area of strength for some children with ADHD, while reading comprehension represented the largest literacy deficit. However, additional ASD trait severity was not shown to exacerbate this reading comprehension deficit. Secondly, the effect of ASD symptoms on the social cognition abilities of adolescents with ADHD was investigated. Each social cognition ability (facial emotion recognition, empathy and theory of mind) were explored in turn with differing results. Social cognition was tested using behavioural tasks, and both FER and empathy were also examined using eye tracking technology. Results showed that ASD symptoms were not found to affect the facial emotion recognition ability of children with ADHD, or alter their eye looking patterns. However, ASD symptoms were shown to have a significant effect on cognitive empathy for fear, alongside reducing the amount of time children spent looking at the eyes and increasing the amount of time spent looking at the face of a character experiencing fear. In the investigation of theory of mind, co-occurring conduct disorder symptoms were also investigated alongside ASD symptoms, as a gap in the literature was identified. Results showed that theory of mind was impaired in children with ADHD compared to controls, and that conduct disorder symptoms seemed to be driving this deficit. ASD symptoms, on the other hand, had no additional effect on performance. Thirdly, the relationship between reading comprehension and social cognition was explored in relation to a sample of adolescents with ASD and typically developing peers. Participants with ASD were found to be impaired in reading comprehension, facial emotion recognition and cognitive empathy compared to controls. In addition, the association between ASD diagnosis and reading comprehension was shown to be mediated by cognitive empathy. Taken together, these results provide a valuable insight into the dimensional overlap between ADHD and ASD, and suggest that practitioners should take co-occurring ASD and conduct disorder symptoms into account when choosing appropriate interventions for young people with ADHD. The findings from our ASD sample additionally indicate that interventions which focus on improving both reading comprehension and social cognition simultaneously could be viable, and should be considered for future implementation into schools to support the learning of individuals with ASD