Background: Williams syndrome (WS) is a rare genetic disorder which results in the uneven cognitive profile and unlike an autistic syndrome (AS) is characterized by good social skills. Despite this syndrome specific profile both syndromes are characterized by impairments in working memory and visuo-spatial cognition. We hypothesized that both syndromes would have impairments in working memory and visuo-spatial cognition at early age, caused by the same reason, but toddlers with WS would have difference in profile of impairments.
Objectives: We examined working memory and visuo-spatial cognition in toddlers with AS and WS in comparison to typically developing children (TDC).
Methods: A-not-B test (Diamond, 1990) was administered to 12 children diagnosed with AS (chronological age (3,6±0,6)), 9 children with WS (3,6±1,2), and 17 TDC (2,1±0,7). Mental age was assessed with Bayley Scales (BSID II, 1993) and Psychological Educational Profile (Schopler et al, 1990). Three groups were matched for mental age. Repeated measures ANOVA was used for statistical analysis.
Results: The results showed that in average the delay in working memory in autistic children was in accordance with their mental age. The WS children showed worse ability to tolerate the delay in AB than both typically developing (TD) and autistic children (AS) matched on mental age. In sharp contrast to both AS and TD groups WS toddlers had problems with maintenance of spatial location of hidden object in their short-term spatial memory. Toddlers with WS had asymmetrical pattern of performance on A-not-B test with the right-handed search errors in simple trials not seen in both AS and TD groups.
Conclusions: Unlike autistic children, toddlers with WS demonstrated a pervasive executive deficit. In addition to worse ability to tolerate the delay in AB toddlers with WS demonstrated left hemisphere deficit in visuo-spatial performance that is not observed in both AS and TD mental age matched groups. This may confirm the hypotheses of left hemisphere impairment in early age Williams syndrome.
See more of: Cognition and Behavior
See more of: Symptoms, Diagnosis & Phenotype