The relevance of autistic traits to sibling relationship quality and psychological adjustment

This thesis in part addressed a call by Hodapp, Glidden & Kaiser (2005) to focus on identifying potential mediators and moderators of the relationship between growing up with a sibling with an autism spectrum condition (ASC) and adverse outcomes such as poorer sibling relationship quality (SRQ) and adjustment problems. It attempted to clarify previous inconsistent findings in the literature by considering autism as a dimensional disorder (with traits present on a continuum between the general population and those on the higher end reaching a clinical cut-off for diagnosis of ASC) and focusing on the autistic traits of (mainly) older siblings in a dyad. Specifically, these related to attention to detail, impaired mind reading ability, impaired social skills and impaired imagination. In addition, when looking at families with an ASC child, using a relatively homogenous sample group of typically developing younger siblings (YS) in middle childhood controlled for factors that potentially influenced past mixed findings. Hypotheses were extended to an analogous sample of young adults by asking dyads for both retrospective and current (adult) SRQ and self reported autistic traits. Themes emerging from the actual lived experiences of typically developing younger siblings of children with autism were also considered, and highlighted a number of difficulties faced by these siblings. The quantitative findings indicate that different elements of the social and communication domains relate to negativity compared to positivity in SRQ, and that there is a significant relationship between attention to detail (i.e. the non-social domain) and typical YS adjustment but not between YS adjustment and the social and communication domains. For young adults, reports of higher impairments in imagination were associated with retrospective reports of lower positivity in SRQ, and level of attention to detail was significantly associated with rivalry in adult SRQ. Overall these findings indicate that different autistic traits should be considered as separate influences on SRQ and adjustment.