Early diagnosis of Autism Spectrum Disorders

The general aim of the SOSO-project (Screenings Onderzoek Sociale Ontwikkeling), which provided the basis for the largest part of this thesis, was to evaluate the early signs and symptoms of Autism Spectrum Disorders (ASDs) in children identified through screening and by surveillance and to determine their potential biological, behavioural, cognitive, and environmental correlates. This particular thesis has its focus on the early diagnosis of ASDs. This subject is divided into 3 separate parts; the first part centers on the feasibility and the value of a diagnostic evaluation of ASDs around two years of age (Chapter 2). The second part is aimed at providing professionals working with this population with a more accessible diagnostic procedure (Chapter 3). Thirdly, we explored the value of biological measures for the phenotype of ASD (Chapter 4, Chapter 5 and Chapter 6). The research data discussed in Chapter 2, Chapter 3, and Chapter 4 are based on the evaluation of children in the SOSO-project. The data presented in Chapter 5 and Chapter 6 originate from a cohort of children, referred with symptoms of ASD before the age of four years as an outpatient to the Department of Child and Adolescent Psychiatry of the University Medical Centre Utrecht.