Affect, Social Behavior, and the Brain in Williams Syndrome

Williams syndrome (WS) is a rare genetic disorder characterized by intellectual impairment and a distinctive physical and neuropsychological profile. Relative to their level of intellectual functioning, individuals with WS exhibit strengths in language and face recognition, with deficits in visual-spatial cognition. A heightened appetitive drive toward social interaction is a strong behavioral feature. Relative to other neurodevelopmental disorders, WS has a clearly defined genetic basis, together with a consistent neurocognitive profile of strengths and deficits. Thus, this disorder offers unique opportunities for elucidating gene–brain–behavior relationships. We focus on manifestations of the unusual social profile in WS, by examining data within and across levels of cognition, brain, and molecular genetics. KEYWORDS—Williams syndrome; genotype–phenotype correlations; cognition; language; sociability Williams syndrome (WS) is a rare genetic neurodevelopmental disorder occurring once in approximately 7,500 live births. Stemming from a deletion (a genetic aberration in which a part of a chromosome is missing) on chromosome 7q11.23, WS causes individuals to show a characteristic physical and neuropsychological profile. The deletion includes the gene ELN, which codes for an important elastic protein (elastin) in connective tissue that is particularly abundant in large blood vessels such as the aorta. Individuals with WS typically have specific cardiac abnormalities, hypersensitivity to sound, and characteristic facial features (Morris & Mervis, 2000; see Fig. 1). Most individuals have mild to moderate intellectual impairment, with more pronounced deficits in performance than verbal IQ (Bellugi, Lichtenberger, Jones, Lai, & St. George, 2000). Our 20-year program of research has outlined an unusual profile of cognitive dissociations in WS: Language represents a relative strength compared to other intellectual abilities. Within visual cognition, face recognition appears remarkably ‘‘spared,’’ whereas other aspects of visual-spatial functioning are severely impaired (Bellugi et al., 2000). The WS personality is characterized by hypersociability, including overfriendliness and heightened approachability toward others, combined with anxiety relating to new situations and objects and a difficulty forming and maintaining friendships with peers. Although variability exists within the WS population, the clear genetic basis presents an unusual opportunity to elucidate gene–brain– behavior relations. Combining developments in human genetics and brain imaging may make it possible to trace gene–brain– cognition linkages using WS as a model. This article focuses on our across-level studies of the affiliative drive in WS. LANGUAGE AS AN INDEX OF SOCIABILITY Children With WS: The Social Use of Language Strangers are often impressed by the language proficiency and sociability of individuals with WS. Losh, Bellugi, Reilly, and Anderson (2000) asked 30 children with WS and a typically developing control group matched for gender and chronological age (4–12) to tell a story from the wordless picture book, Frog, Where Are You? The transcribed stories were coded separately for grammar and for the social and affective use of language (evaluative language). Evaluative language refers to language reflecting the narrator’s attitude or perspective, including attributing emotions or motivations to characters, using intensifiers (really, very, so) and sound effects, direct quotes, and character speech. A new category called ‘‘audience hookers,’’ referring to devices used to capture and maintain the listener’s attention (‘‘Lo and behold! There were froglets!’’), was developed for the evaluative-language coding system to characterize a Address correspondence to Ursula Bellugi, Laboratory for Cognitive Neuroscience, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd., La Jolla, CA 92037; e-mail: [email protected]. CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE Volume 16—Number 2 99 Copyright r 2007 Association for Psychological Science language function unique to WS. The findings showed that children with WS made significantly more grammatical errors than did their typical peers. In fact, their grammatical performance did not differ proportionally from that of chronologicalage-matched children with specific language impairment (Reilly, Losh, Bellugi, & Wulfeck, 2004). Nonetheless, their stories contained significantly more social and affective evaluative devices (see Fig. 2). Given the high frequency of grammatical errors by the children with WS, and because evaluative devices require linguistic flexibility and presuppose a certain level of mastery, this raises interesting questions about the relationship between the acquisition of linguistic structure and the use of language for social purposes in WS. Adolescents With WS: The Social Use of Language In one of the first language studies on WS (Reilly, Klima, & Bellugi, 1990), we asked adolescents with WS (aged 10–18 years), ageand IQ-matched adolescents with Down syndrome, and mental-age-matched typically developing children to narrate the Frog story. Stories were analyzed for grammar and evaluative language. The adolescents with WS were relatively proficient, specifically in their use of grammar. The WS group used evaluative language significantly more frequently than did the typically developing controls or the adolescents with Down syndrome. Consistent with the child study (Losh et al., 2000), these results demonstrate the excessively social use of language in WS. Participants with WS exceed their typically developing peers in the use of social evaluation at all ages, and this effect has also been observed across different languages and cultures. Table 1 includes examples from both WS and typically developing children to illustrate how the use of social evaluation differs qualitatively between the groups. For individuals with WS, structural language proficiency is not necessary for extensive use of social evaluation. Indeed, as soon as children with WS are able to produce simple narratives, they exploit their linguistic abilities maximally for social purposes. NONLINGUISTIC SOCIAL-BEHAVIORAL PROFILE IN WS At the heart of the enigma surrounding WS is the enhanced drive toward social interaction. We elucidate its nature by examining data from three sources: (a) parental report forms, (b) an experiment assessing willingness to approach strangers, and (c) social interaction of toddlers with WS. Sociability in WS Using Parental Questionnaire The Salk Institute Sociability Questionnaire (SISQ) solicits information from parents of children with WS concerning their child’s (a) willingness to approach other people (familiar and unfamiliar), (b) behavior in social settings, (c) ability to remember faces and names, (d) eagerness to please other people, (e) empathy, and (f) frequency with which others approach the individual. The analysis produces three composite scores: Global Sociability (a cross-domain measure of sociability); Social Approach and its two sub-scores, Approach Strangers and Approach Familiars; and Social-Emotional. Doyle, Bellugi, Korenberg, and Graham (2004) used the SISQ to examine social behaviors in children with WS and Down syndrome and typically developing children matched for chronological age. Findings showed that the WS group was rated significantly higher than typically developing controls on all aspects of sociability. Moreover, children with WS significantly exceeded the Down syndrome group on nearly every rating, even when the data were analyzed by age category (Fig. 3). Consistent with the child study, findings from another study utilizing the SISQ showed that adults and adolescents with WS were rated significantly higher on all aspects of sociability, compared to chronological-age-matched typically developing individuals and those with Down syndrome (Jones et al., Fig. 1. Children with Williams syndrome (WS). The specific facial features of WS include broad brow, full nasal tip, star-shaped or lacy iris, flat nasal bridge, prominent lips, full cheeks, and wide mouth. (Pictures used with permission.) Fig. 2. Frequency of social-evaluation devices (expressive language reflecting the narrator’s attitude or perspective) in narratives from typically developing children and children with Williams syndrome (aged 4–12 years). Individuals with WS use social evaluation significantly more frequently than controls, at all ages studied. 100 Volume 16—Number 2 Williams Syndrome