Characteristics of ASD in Adults with Williams Syndrome

Background:  Williams syndrome (WS), a rare developmental disorder caused by deletion at 7q11.23, is generally characterized by excessive socialization and communication (over-friendliness and talkativeness). While this over-socialization is sometimes thought to be antithetical to the stereotypical under-socialization of autism spectrum disorder (ASD), prior research has shown that many young children with WS also show significant symptoms of ASD and may meet diagnostic criteria for ASD based on observational and parent reports. Little work has been done on the social functioning and repetitive behaviors in adults with WS and little is known about the overlap of WS and ASD in an adult population.

Objectives:  This study aims to explore the prevalence of ASD in adults with WS and understand the characteristics of those who meet criteria for both disorders

Methods: Data for this study are taken from an ongoing genetics, neuroimaging, and behavioral study of adults with William’s syndrome. Preliminary information is based on the first eight participants. 20 participants are expected by April 2017. The Autism Diagnostic Rating Scale, second edition (ADOS) was conducted by a research reliable clinician. Participants also completed a wide range of behavioral, emotional, and cognitive measures, including the Social Responsiveness Scale (SRS; parent report), the Wechsler Adult Intelligence Scale, 3^rd edition (WAIS), the Peabody Picture Vocabulary Test (PPVT) and the Expressive Vocabulary test (EVT).

Results:  In this sample, two participants (25%) received an ADOS classification of Autism, and one (13%) received a classification of Autism Spectrum. Five participants received non-spectrum classifications. Participants who showed significant ASD symptoms on the ADOS also had significantly higher SRS Social Communication scores, but did not show different SRS Repetitive and Restrictive Behavior scores from the non-spectrum participants. Verbal IQ and receptive and expressive vocabulary scores had an inverse relationship with ADOS scores and were the best predictor of autism spectrum classification.

Conclusions:  Despite differences in social presentation, many adults with Williams syndrome also show significant symptoms of ASD. These symptoms seem to be mainly focused in the social communication domain of ASD, and observational measures and parent report measures line up well. The level of repetitive behaviors and interests in adults with WS does not seem to adequately discriminate those with ASD and those classified as non-spectrum. As has been shown in previous research, verbal IQ and vocabulary scores seem to be a relatively good predictor of social communication deficits in this population. Overall, a significant portion of adults with Williams syndrome may be experiencing social communication dysfunction that reaches a clinically significant level and likely requires attention and intervention.