Latent structure of the autism phenotype

The Empathising-Systemising (E-S) theory of autism argues that the persistent deficits in communication and social interaction in autism spectrum conditions (ASC)1 can be accounted for by an impairment in empathy, whilst the repetitive behaviours and narrow interests can be explained by a strong drive to understand and derive rules about a system; namely systemising. Autistic traits are thought to follow a continuous distribution, with individuals with autism represented at the more severe end of this spectrum. Furthermore, subthreshold traits have also been identified in first-degree relatives of individuals with ASC, termed the broader autism phenotype (BAP). While there has been some research assessing the cognitive and behavioural symptoms associated with the autism spectrum using clinical samples, no studies to date have simultaneously evaluated the autism phenotype amongst individuals with a clinical diagnosis of ASC, first-degree relatives and community samples. This thesis uses structural equation modelling to evaluate the E-S theory of autism in order to understand the latent structure of the autism phenotype. Furthermore, it seeks to determine whether the latent structure of the autism phenotype is consistent amongst three groups stratified by genetic vulnerability: individuals with an autism diagnosis, parents of a child with ASC, and general population controls.