The relationship between executive function (EF) and social difficulties in children and adolescents with autism spectrum disorder (ASD) is investigated in the current thesis. Executive dysfunction is one of the cognitive theories of ASD. Even though it cannot explain all of the symptoms of ASD, executive dysfunction is a central characteristic of everyday functioning in ASD and closely related to adaptive functioning and quality of life. Few studies, however, have investigated the relationship between EF and social function in everyday life in this group. Sub-aims of this thesis were to examine how sex and comorbid attention deficit/ hyperactivity disorder (ADHD) affect the relationship between social function and EF. The role of EF by means of genetic information is also examined. We had access to polygenic scores (PGSs) for ASD, ADHD and general intelligence, and explored their association to executive dysfunction in everyday life.
The first aim was to investigate the relationship between everyday EF as measured by the Behavior Rating Inventory of Executive Function (BRIEF) and social function as measured by the Social Responsiveness Scale questionnaire (SRS). In a sample of 86 children and adolescents (23 girls), we found that difficulties with the metacognitive aspects of EF were significantly related to social dysfunction (Paper I). This finding remained even after the children with comorbid ADHD were excluded from the analyses. Secondly, we wanted to examine possible sex differences in the relationship between executive dysfunction as measured by the BRIEF and autistic symptoms using the Autism Diagnostic Interview-Revised (ADI-R). The results showed a strong and significant association between BRIEF scores and ADI-R domains for social interaction and communication in girls, but not for boys. We did not find sex differences in the relationship between executive dysfunction and restricted and repetitive behaviors (Paper II). Comorbid ADHD did not have a significant impact on the association between BRIEF and ADI-R scores.
The last aim was to explore if the polygenic score (PGS) for ASD was associated with executive dysfunction in everyday life in a clinical sample of children and adolescents admitted for clinical assessment of ASD. In addition, we had access to the PGSs for ADHD and general intelligence (INT) for the same participants. The sample was divided into low and high groups based on their PGSs. In a regression model, we found that ASD PGS was significantly associated with behavior regulation aspects of EF. We did not find any significant association between EF and the PGSs for ADHD or INT in our sample (Paper III). Furthermore, we found high PGS for general intelligence to be related to social difficulties in everyday life measured by the SRS.
One possible clinical implication of our findings is that metacognitive aspects of EF may be of particular importance for social function in everyday life for children and adolescents with ASD. Interventions targeting metacognitive skills could therefore have a positive influence on social function for these children.
Furthermore, there might be important differences between girls and boys in the relationship between executive dysfunction and reciprocal social interaction and communication. Our results indicated that the relationship for girls was stronger than for boys. This might imply that executive dysfunction and social difficulties in girls may be more closely related, and that girls with ASD may benefit more from EF interventions.
Lastly, children and adolescents with high PGS for ASD might be particularly vulnerable and have more difficulties with behavior regulation aspects of EF than those with low PGS for ASD. The clinical relevance may be that preventions aimed at EF difficulties could be offered to children at risk earlier, and that the more general ASD treatment could be stratified according to PGS level.