title: Prevalence of autism spectrum disorder symptomatology and related behavioural characteristics in individuals with Down syndrome.
abstract: We evaluated the proportion of individuals with Down syndrome (DS: N = 108) who met criteria for autism spectrum disorder (ASD) on the Social Communication Questionnaire and the severity of ASD-related symptomatology in this group. The proportions of individuals with DS meeting the cut-off for ASD and autism in this sample were 19% and 8%, respectively. We then evaluated the behavioural profile of individuals with DS who scored above cut-off for ASD (DS+ASD; N = 17) compared with those with DS-only (N = 17) and individuals with idiopathic ASD (N = 17), matched for adaptive behaviour skills and ASD symptom severity (ASD group only). Individuals in the DS+ASD and ASD-only groups showed more stereotyped behaviour, repetitive language, overactivity and self-injury than the DS-only group (p < .001). Individuals in the DS+ASD and DS-only groups appeared less withdrawn from their surroundings than those with ASD (p < .004). These findings indicate differences in the behavioural and cognitive profile of individuals with DS+ASD compared with those with DS-only, when controlling for adaptive behaviour skills. Individuals with DS+ASD show broad similarities with individuals with idiopathic ASD with regard to ASD and behavioural characteristics but may also show some areas of subtle difference from this group.
authors.affiliation: Cerebra Centre for Neurodevelopmental Disorders, School of Psychology, University of Birmingham, UK. j.f.moss@bham.ac.uk
authors.forename: Jo
authors.initials: J
authors.lastname: Moss
authors.forename: Caroline
authors.initials: C
authors.lastname: Richards
authors.forename: Lisa
authors.initials: L
authors.lastname: Nelson
authors.forename: Chris
authors.initials: C
authors.lastname: Oliver
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000523:psychology; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000453:epidemiology / Q000523:psychology; D002675:Child, Preschool; D004314:Down Syndrome / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D015995:Prevalence; D012919:Social Behavior; D013239:Stereotyped Behavior; D055815:Young Adult