Objectives: The purpose of this study is to examine classification of children with WS on the ADOS according to the newly published ADOS algorithms.
Methods: 29 children with WS (mean age=41.59 months, SD=8.95 months) were administered Module 1 of the ADOS and the Mullen Scales of Early Learning (MSEL). The ADOS administrations were scored according to the original and the newly published algorithms.
Results: Originally, 14/29 (48.3%) of the children with WS met or exceeded the cutoff score for an ASD (Klein-Tasman et al., 2008). With the use of the new algorithm, 16/29 (55.2%) children met or exceeded the cutoff score. In total, the classification of 10 children in the sample changed when the new algorithm was used: 4 of these children were originally classified as ASD and moved to nonspectrum, while 6 were originally nonspectrum and moved to ASD. Although a significant relationship was found between verbal ability and classification using the old algorithm cutoff scores, this relationship was not found when the new algorithm was used.
Conclusions: The use of new algorithm cutoff points identified a slightly higher percentage of children with WS who exhibit behaviors consistent with ASDs. One third of the participants with Williams syndrome changed classification with the use of the new algorithm. The new algorithm appears to be more effective at identifying social difficulties independent of language. This is especially important in WS, as studies have found that children in this population often have language difficulties early in development (Mervis & Robinson, 2000). Additional implications will be discussed.