Autism spectrum disorder diagnoses in Stockholm preschoolers.

The aims of this study were to estimate prevalence rates of children with autism spectrum disorder (ASD) diagnoses in a cohort of 6-year-old children with birth year 2002, referred to the Autism Centre for Young Children, serving the whole of Stockholm county and on the basis of the available data discuss clinical aspects of assessment, habilitation and follow-up. Records of 142 of a total of 147 (123 boys and 24 girls) identified children with ASD diagnoses were scrutinised with respect to type of diagnosis, cognitive level, other developmental disorders and medical/neurological disorders. The overall prevalence of such disorders was 6.2/1000 (95% confidence interval 5.2-7.2/1000). The rates of learning disability/mental retardation, developmental delay without a specified cognitive level and normal intelligence constituted about one third, respectively. AS and atypical autism tended to be diagnosed more often at age 5-6 years while AD with learning disability/mental retardation was more often diagnosed at age 3-4 years. The awareness of ASDs has resulted in increasing numbers of children being diagnosed at young ages. We conclude that it is important to take into account these children's broader developmental profiles, need for repeated assessment of cognitive functions and follow-up over time and also the requirement for medical/neurological consideration and work-up.