Symptoms of Autism Spectrum Disorder in Individuals with Down Syndrome or Williams Syndrome

Background:  Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by persistent deficits in social communication, as well as restricted, repetitive patterns of behavior (American Psychiatric Association, 2013). Despite past research demonstrating that individuals with Down syndrome (DS) are not impaired on the social domain, and that Williams syndrome (WS) is a polar opposite of autism, individuals with these conditions display an increased prevalence of ASD. Previous research has shown that not only do more individuals with Down syndrome have a comorbid diagnosis of ASD in comparison to the reported CDC prevalence, but many children who do not receive an ASD diagnosis still exhibit elevated ASD symptoms. Research investigating the overlap of WS and ASD has shown that individuals with WS also display an increased prevalence of ASD, and display elevations both on assessments measuring symptoms of autism (Lough et al., 2015), and gold-standard autism diagnostic assessments (Klein-Tasman, Phillips, Lord, Mervis, & Gallo, 2009).

Objectives:  The objective of this study is to investigate the overlap of symptoms associated with autism within the Down syndrome and Williams syndrome population, utilizing an autism screener (the Social Communication Questionnaire, SCQ), a dimensional measure of symptoms associated with autism (the Autism Spectrum Rating Scales, ASRS), and an adaptive behavior assessment (the Adaptive Behavior Assessment System, Third Edition, ABAS-3).

Methods:  Parents and primary caregivers of children aged 6-18 with either an ASD, Down syndrome, or Williams syndrome diagnosis were asked to fill out an anonymous online survey, which contained demographic questions, as well as the aforementioned assessments. The goal is to recruit at least 28 individuals for each group, and to continue to recruit until we have received 75 per group. Currently, 77 parents of children with DS, 34 parents of children with WS, and 5 parents of children with an ASD diagnosis have completed the survey.

Results: Preliminary analyses show that more individuals with Down syndrome and Williams syndrome screened positive on the SCQ, in comparison to the population prevalence reported in previous research (Chandler et al., 2007). In this sample, 22% of individuals with a DS diagnosis screened positive on the SCQ (5 of the 77 individuals in the sample had a comorbid diagnosis of ASD, and all screened positive on the SCQ). Additionally, 53% of individuals with a WS diagnosis screened positive on the SCQ (4 of the 34 individuals in the sample had a comorbid diagnosis of ASD, and all screened positive on the SCQ). Additional analyses will compare the total score on the ASRS to the normative sample mean, examine the role of adaptive behavior in total scores on the ASRS, and compare each group’s total scores on the three subscales: social/communication, unusual behaviors and self-regulation.

Conclusions:  It is our hope that results of this study will shed light on the phenotypic overlap between autism and these genetic conditions, and will develop future directions for new research in how to best screen, diagnose, and create interventions for individuals with DS or WS who also display characteristics of ASD.