BackgroundPrevalence estimates of autism spectrum disorder (ASD) in Down syndrome (DS) are highly varied. This variation is partly due to the difficulty of screening for and diagnosing comorbid ASD in individuals with a syndrome that carries its own set of social communicative and behavioral difficulties that are not well documented. The aim of this study was to identify the typical range of social communicative impairments observed in children, adolescents, and young adults with DS who do not have comorbid ASD.MethodsWe examined patterns of scores from the five subscales of the Social Responsiveness Scale (SRS) in 46 individuals with DS (ages 10–21 years) without comorbid ASD relative to the published normative sample. We also explored the correlations between SRS symptomatology and age, nonverbal cognition, and receptive language.ResultsSRS scores were elevated (i.e., more ASD symptoms endorsed), with mean scores falling into the clinically significant range. Analysis by subscale revealed a specific pattern, with Autistic Mannerisms and Social Cognition scores significantly more elevated than Social Communication scores, which were significantly more elevated than Social Awareness and Social Motivation scores. Correlations between SRS scores and the other measures varied by subscale.ConclusionsGeneral elevated ASD symptomatology on the SRS indicates the need for developing population-based norms specific to DS. The pattern of scores across subscales should inform clinicians of the typical range of behaviors observed in DS so that individuals with atypical patterns of behavior can be more easily identified and considered for a full ASD evaluation.

Background Previous research has indicated a unique profile of executive function (EF) in children and adolescents with Down syndrome (DS). However, there is a paucity of research on EF in adults with DS. This study aimed to gain a broader understanding of strengths and weaknesses in EF in DS from 2–35 years. Method Parents of 112 individuals with DS between 2–35 years participated in this study. Parents either completed the Behavior Rating Inventory of Executive Function—for individuals 6+ years—or the BRIEF-Preschool—for children 2–5 years. Results Results suggest overall difficulties, but also patterns of strength and weakness, within EF for individuals with DS. For the 2–5-year-old group, Emotional Control and Shift were relative strengths, Planning/Organization and Inhibit were intermediate skills, and Working Memory was a relative weakness. For the 6–18-year-old group, Emotional Control and Organization of Materials were relative strengths, Inhibit and Initiate were intermediate skills, and Working Memory, Monitor, Planning/Organization, and Shift were relative weaknesses. Most abilities were consistent from 2–18 years, except Shift, which decreased in preadolescence before beginning to recover in adolescence. Across the full age range (2–35 years), composite scores indicated quadratic trends in Inhibit, Working Memory, and Planning/Organization, and a cubic trend in Shift, with EF abilities generally declining in middle childhood before recovering in adulthood. Conclusions This study extends previous research on EF in DS by providing an initial description of EF profiles across the lifespan. More longitudinal and behavioural research is needed to further characterise the development of EF in DS.