Comorbidity of autistic spectrum disorders in children with Down syndrome

The aim of the study was to identify the comorbidity of autistic spectrum d isorders in a population of children with Down syndrome (DS), All children with DS within a defined population of South Birmingham were identified. Th e Asperger Syndrome Screening Questionnaire and the Child Autism Rating Sca le were completed and diagnosis made according to ICD-10 criteria following interview and observation, Thirty-three of 58 identified children complete d the measures, four of whom received a diagnosis of an autistic spectrum d isorder. This is equivalent to a minimum comorbid rate of 7%. The questionn aire items concerning social withdrawal, restricted or repetitive interests , clumsiness, and unusual eye contact were associated with an autistic diso rder, Of the remaining 29 participating children, 11 also displayed marked obsessional and ritualistic behaviours, The comorbid occurrence of autism a nd DS is at least 7%. It is important that these children are identified an d receive appropriate education and support. A full assessment of social, l anguage, and communication skills and behaviour is crucial, particularly in children with DS who appear different from other children with DS. Potenti al mechanisms accounting for this comorbidity are discussed.