In-depth profile analysis and developmental trends in Wechsler performance among individuals with Williams syndrome.

Abstract

Williams syndrome is caused by a microdeletion of genes on chromosome 7q11.23. It is estimated that 75% of individuals with Williams syndrome meet criteria for intellectual disability. The existing literature, primarily using the Differential Ability Scales, supports a pattern of relative weakness in visuospatial construction and language abilities commensurate with or slightly stronger than overall cognitive functioning. However, it is unclear how cognitive profile patterns are captured by current versions of the Wechsler system of assessment, which is more commonly used in community settings. Further, few longitudinal data on cognitive profiles exist, limiting conclusions about developmental trends. The current study included 59 individuals with Williams syndrome aged 4-24 years assessed with the age-appropriate Wechsler test a median of twice over 3 ± 1.5 years. The results of this study confirmed the profile found in the extant literature, but there was evidence of heterogeneity in relative strengths and weaknesses that necessitates individual evaluation. Careful longitudinal modeling of between- and within-person effects suggested stability of standard scores in all domains. The results of this study inform a developmental understanding of the Williams syndrome cognitive profile and improve the interpretability of research findings for clinical and school settings where the Wechsler system is commonly used.