NR326 Research Article Mental Retardation 3 Essay

NR326 Research Article Mental Retardation 3 Essay

NR326 Research Article Mental Retardation 3 Essay

ORIGINAL ARTICLE

Screening for autism spectrum disorder in children with Down syndrome: An evaluation of the Pervasive Developmental Disorder in Mental Retardation Scale Vincent Pandolfia, Caroline I. Magyarb and Charles A. Dillc

aPsychology Department, Rochester Institute of Technology, Rochester, NY, USA; bDepartment of Paediatrics, Division of Neurodevelopmental and Behavioural Paediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA; cPsychology Department, Hofstra University, Hempstead, NY, USA

ABSTRACT Background Children with Down syndrome (DS) are at risk for autism spectrum disorder (ASD). They are often diagnosed later than other children in part due to difficulty differentiating ASD-related impairment from that associated with DS. The psychometric properties of the Pervasive Developmental Disorder in Mental Retardation Scale (PDD-MRS) were examined with the aim of informing ASD screening guidelines for children with DS. Method Analysis of archival data from children aged 3 to 15 years with DS (N = 386) evaluated the reliability and validity of the PDD-MRS. Results Factor analyses yielded 2 factor-based scales: ASD and Emotional and Behavioural Problems. ASD reliably assessed ASD-specific symptoms, correlated with other ASD measures, and demonstrated good diagnostic accuracy. Emotional and Behavioural Problems assessed problems not diagnostic of ASD but may reflect part of the behavioural phenotype of DS and ASD. Conclusion The PDD-MRS appears to have utility in ASD screening for this population.

KEYWORDS autism; ASD; Down syndrome; PDD-MRS; assessment

Introduction

Research suggests the prevalence of autism spectrum dis- order (ASD) in children with Down syndrome (DS) may be higher than that observed in the general population. Estimates range from 5% to 39% (for a review, see Moss & Howlin, 2009; Reilly, 2009); many children with DS are diagnosed at a later age relative to other chil- dren and some may not be identified at all (e.g., Howlin, Wing, & Gould, 1995; Rasmussen, Börjesson, Wentz, & Gillberg, 2001). This situation is concerning, particularly as research indicates that children with DS and co-occur- ring ASD have lower cognitive, language, and adaptive levels, and have more behaviour problems than children with DS only (e.g., Magyar, Pandolfi, & Dill, 2012; Mol- loy et al., 2009), suggesting that the co-occurrence of ASD conveys additional morbidity. If not identified with a co-occurring ASD, then the child is unlikely to receive ASD-specific treatment.

Although the exact reasons for the late or lack of ASD diagnosis is unknown, it has been speculated that the sig- nificant delays and impairments seen in children with DS in the areas of communication and behaviour are attrib- uted to the child’s level of intellectual disability (ID) and associated speech and language impairments. These pro- blems are not viewed as symptomatic of a co-occurring ASD, a phenomenon called diagnostic overshadowing

(Reiss, Levitan, & Szyszko, 1982). However, the literature containing descriptions of children with DS and co- occurring ASD (DS + ASD) and those without ASD (DS) suggests that (a) heightened severity of impairment, and (b) differences in the form of the social communi- cation and repetitive behaviour can distinguish ASD- related impairments from those related to ID. This is more likely if a developmental approach to ASD assess- ment is applied (Dosen, 2005; Hepburn, Philofsky, Fidler, & Rogers, 2008) and if reliable and valid ASD assessment measures are used (e.g., Magyar et al., 2012).

The distinction between ASD-related symptomatol- ogy and DS-related impairment can be seen in both the social communication and repetitive behaviour domains of an ASD diagnosis. These include the pres- ence of more stereotyped and repetitive speech forms (when speech is present), limited or no gesturing for communicative purposes, limited interest in peers, increased probability of aggression in response to social approaches by peers, the absence of pretend and imagi- native play, the absence of functional play, such as demonstrating the tendency to line objects up, and pre- occupation with parts of objects (e.g., see Channell et al., 2015; Hepburn et al., 2008; for a review, see Reilly, 2009). These findings contribute greatly to advancing our knowledge of the potential clinical indicators that can