One of the most intriguing characteristics of Williams Syndrome individuals is their hypersociability. The amygdala has been consistently implicated in the etiology of this social profile, particularly given its role in emotional and social behavior. This study examined amygdala volume and symmetry in WS individuals and in age and sex matched controls. Magnetic resonance imaging scans were obtained on a GE 1.5-T magnet with 1.5-mm contiguous slices and were used to measure whole gray matter, white matter and cerebrospinal fluid volumes, as well as amygdala volume (right and left). Results revealed significantly reduced intracranial volume in individuals with WS, compared with controls. There were no differences between groups in absolute amygdalae volume, although there was a relative increase in amygdalae volumes, when adjusted for total intracranial content. There were no inter-hemispheric differences in amygdalae volumes in both groups. These results suggest a relative increase in amygdala volume in WS compared with healthy controls that likely reflects abnormal neurodevelopmental processes of midline brain structures.

Smith-Magenis Syndrome (SMS) is a genetic neurodevelopmental disorder caused by a microdeletion on chromosome 17p11.2. This syndrome is characterized by a distinctive profile of physical, medical and neuropsychological characteristics. The latter include general mental disability, with the majority of individuals falling within the mild to moderate range. This study reports a detailed cognitive assessment of children and adults with SMS with the use of the Wechsler intelligence scales at three distinct levels of analysis: full scale IQ, factorial indices, and subtests. Child and adult samples were each compared to samples of age and gender-matched typically developing individuals. To our knowledge, this is the first study to systematically analyse the cognitive profile of individuals with SMS in Southern Europe. The present study confirmed mental disability, particularly within the moderate category, as a consistent feature of children and adults with SMS. Furthermore, both child and adult samples evidenced significant impairments in all four indices when compared with their typically developing counterparts. A specific pattern of strengths and weaknesses was discernible for both samples, with Verbal Comprehension emerging as a relative strength, whereas Working Memory appeared as a relative weakness. Finally, with the exception of two subtests in the perceptual domain, we found no evidence for a general cognitive decline with age.

Williams syndrome is characterized by impairments in executive functions (EFs). However, it remains unknown how distinct types of EFs relate to intelligence in this syndrome. The present study analyzed performance on working memory, inhibiting and shifting, and its links to IQ in a sample of 17 individuals with WS, and compared them with a group of 17 typically developing individuals matched on chronological age and gender. In conclusion, our results suggest that working memory, inhibiting, and shifting relate differently to intelligence in WS as well as in typical development, with working memory being the EF most closely related to intelligence in both groups. Notably, the magnitude of the associations between the three EFs and IQ was substantially higher in the WS group than in the TD group, bringing further confirmation to the notion that frontal lobe impairments may produce a general compromise of several EFs.

This study compares narrative production among three syndromes with genetic microdeletions: Williams syndrome (WS), Smith-Magenis syndrome (SMS), and Prader-Willi syndrome (PWS), characterized by intellectual disabilities and relatively spared language abilities. Our objective is to study the quality of narrative production in the context of a common intellectual disability. To elicit a narrative production, the task Frog! Where Are You was used. Then, structure, process, and content of the narrative process were analysed in the three genetic disorders: WS (n52), SMS (n52), and PWS (n52). Data show evidence of an overall low narrative quality in these syndromes, despite a high variability within different measures of narrative production. Results support the hypothesis that narrative is a highly complex cognitive process and that, in a context of intellectual disability, there is no evidence of particular 'hypernarrativity' in these syndromes.

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