Executive function as measured by the Behavior Rating Inventory of Executive Function-2: children and adolescents with Williams syndrome.

BACKGROUND: Difficulties with executive functions (EF) are very common among individuals with Williams syndrome (WS). To characterise the pattern of relative strengths and weaknesses in EF for children and adolescents with WS, we considered the performance of a large sample on the parent version of the Behavior Rating Inventory of Executive Function-2 (BRIEF-2). Associations between distinct components of EF and adaptive behaviour, behaviour problems and intellectual ability were investigated. The concurrent effects of components of behaviour regulation and emotion regulation on attention problems and anxiety problems also were evaluated. METHODS: Participants were 308 6-17-year-olds with genetically confirmed classic WS deletions. Parent report of EF was measured by the BRIEF-2 questionnaire. Most participants (223/308) completed the Differential Ability Scales-II as a measure of intellectual ability. The parents of these individuals also completed the Child Behavior Checklist and the interview form of the Scales of Independent Behavior-Revised. RESULTS: As a group, the participants evidenced considerable parent-reported EF difficulty. A profile of relative strength and weakness was found at the index level, with performance on both the Behavior Regulation Index and the Emotion Regulation Index significantly better than performance on the Cognitive Regulation Index. Within each index, a statistically significant pattern of relative strength and weakness also was identified. Difficulties with behaviour regulation and emotion regulation were related to both behaviour problems and adaptive behaviour limitations. Higher inflexibility and more difficulty with self-monitoring were associated with lower overall intellectual ability. Difficulty with inhibition was uniquely associated with attention problems, and inflexibility was uniquely associated with anxiety problems. CONCLUSIONS: Executive function difficulties are highly prevalent among children and adolescents with WS and are associated with adaptive behaviour limitations, both internalising and externalising behaviour problems and more limited intellectual ability. These results highlight the importance of designing and delivering research-based interventions to improve the EF of children and adolescents with WS.

Predictors of specific phobia in children with Williams syndrome.

BACKGROUND: Specific phobia (SP) is the most common anxiety disorder among children with Williams syndrome (WS); prevalence rates derived from Diagnostic and Statistical Manual of Mental Disorders-based diagnostic interviews range from 37% to 56%. We evaluated the effects of gender, age, intellectual abilities and/or behaviour regulation difficulties on the likelihood that a child with WS would be diagnosed with SP. METHODS: A total of 194 6-17 year-olds with WS were evaluated. To best characterise the relations between the predictors and the probability of a SP diagnosis, we explored not only possible linear effects but also curvilinear effects. RESULTS: No gender differences were detected. As age increased, the likelihood of receiving a SP diagnosis decreased. As IQ increased, the probability of receiving a SP diagnosis also decreased. Behaviour regulation difficulties were the strongest predictor of a positive diagnosis. A quadratic relation was detected: The probability of receiving a SP diagnosis gradually rose as behaviour regulation difficulties increased. However, once behaviour regulation difficulties approached the clinical range, the probability of receiving a SP diagnosis asymptoted at a high level. CONCLUSION: Children with behaviour regulation difficulties in or just below the clinical range were at the greatest risk of developing SP. These findings highlight the value of large samples and the importance of evaluating for nonlinear effects to provide accurate model specification when characterising relations among a dependent variable and possible predictors.

Intracranial arteries in individuals with the elastin gene hemideletion of Williams syndrome.

BACKGROUND AND PURPOSE: Williams syndrome, a rare genetic disorder with a striking neurobehavioral profile characterized by extreme sociability and impaired visuospatial construction abilities, is caused by a hemideletion that includes the elastin gene, resulting in frequent supravavular aortic stenosis and other stenotic arterial lesions. Strokes have been reported in Williams syndrome. Although the extracranial carotid artery has been studied in a sample of patients with Williams syndrome, proximal intracranial arteries have not. MATERIALS AND METHODS: Using MRA, we studied the intracranial vessels in 27 participants: 14 patients with Williams syndrome (age range, 18-44 years; mean age, 27.3 ± 9.1; 43% women) and 13 healthy control participants with similar age and sex distribution (age range, 22-52 years; mean age, 33.4 ± 7.6; 46% women). All participants with Williams syndrome had hemideletions of the elastin gene. Blinded to group allocation or to any other clinical data, a neuroradiologist determined the presence of intracranial vascular changes in the 2 groups. RESULTS: The Williams syndrome group and the healthy control group had similar patency of the proximal intracranial arteries, including the internal carotid and vertebral arteries; basilar artery; and stem and proximal branches of the anterior cerebral artery, MCA, and posterior cerebral arteries. The postcommunicating segment of the anterior cerebral artery was longer in the Williams syndrome group. CONCLUSIONS: Despite the elastin haploinsufficiency, the proximal intracranial arteries in Williams syndrome preserve normal patency.

Adaptive behavior of 4- through 8-year-old children with Williams syndrome.

The adaptive behavior of forty-one 4- through 8-year-olds with Williams syndrome was assessed using the Vineland Adaptive Behavior Scales-Interview Edition. Based on the cognitive and personality profiles characteristic of children with this syndrome, we predicted that the domains of Socialization and Communication would be relative strengths, whereas Daily Living Skills and Motor Skills would be relative weaknesses. We also expected that Socialization Skills would be more advanced than Communication skills, and that within the Socialization domain, interpersonal skills would be stronger than play/leisure or coping skills. All predictions were confirmed. Adaptive behavior standard score was not related to CA. The children earned similar overall standard scores on the Vineland and the Differential Ability Scales. Interrelations among adaptive behavior, cognitive abilities, and personality characteristics are discussed.

The Williams syndrome cognitive profile.

Williams syndrome is a rare neurodevelopmental disorder caused by a hemizygous deletion of approximately 1.5 megabases on chromosome 7q11.23. In this article, we outline a Williams Syndrome Cognitive Profile (WSCP) that operationalizes the cognitive characteristics of the syndrome using measures of absolute and relative performance on subtests of the Differential Abilities Scales (Elliot, 1990a). Testing confirmed excellent sensitivity and specificity scores for the WSCP. Seventy-four of 84 individuals with Williams syndrome fit the WSCP while only 4 participants in a contrast group met all of the WSCP criteria. It was also found that the WSCP does not vary greatly with chronological age or overall level of cognitive ability for individuals with Williams syndrome. Possible applications for the WSCP include psychoeducational evaluation and empirical research such as the search for genotype/phenotype relations in this genetically based syndrome.

Expressive vocabulary ability of toddlers with Williams syndrome or Down syndrome: a comparison.

School-aged children and adults with Williams syndrome have repeatedly been found to evidence an expressive vocabulary advantage relative to same-aged individuals with Down syndrome. However, Singer Harris, Bellugi, Bates, Jones, and Rossen (1997) argued that this advantage is reversed during the initial period of language acquisition; during this time, children with Down syndrome have larger expressive vocabularies than children with Williams syndrome. This result may have been due to methodological problems, however. This study uses a different design to reconsider the question of whether toddlers with Williams syndrome show an expressive vocabulary advantage over same-aged toddlers with Down syndrome. Parents of twenty-four 2-year-olds with Williams syndrome and twenty-eight 2-year-olds with Down syndrome completed the vocabulary checklist from the MacArthur Communicative Development Inventory: Words and Sentences. The 2 groups were carefully matched for chronological age (CA). Results indicated that the toddlers with Williams syndrome had substantially and significantly larger expressive vocabulary sizes than did the CA-matched children with Down syndrome. Additional analyses of children for whom data were available between the ages of 2 years 0 months and 2 years 3 months indicated that the expressive vocabulary advantage for children with Williams syndrome was present even at this very young age when none of the children had begun to produce word combinations. The Discussion section that follows addresses the discrepancy between these findings and those of Singer Harris et al. and considers the variability present within both the Williams syndrome and Down syndrome samples. Also discussed is the continuity across the lifespan in both the expressive vocabulary advantage shown by individuals with Williams syndrome relative to same-aged individuals with Down syndrome and the expressive vocabulary variability within each syndrome.

Williams syndrome: cognition, personality, and adaptive behavior.

Williams syndrome is caused by a microdeletion of at least 16 genes on chromosome 7q11.23. The syndrome results in mild to moderate mental retardation or learning disability. The behavioral phenotype for Williams syndrome is characterized by a distinctive cognitive profile and an unusual personality profile. Relative to overall level of intellectual ability, individuals with Williams syndrome typically show a clear strength in auditory rote memory, a strength in language, and an extreme weakness in visuospatial construction. The personality of individuals with Williams syndrome involves high sociability, overfriendliness, and empathy, with an undercurrent of anxiety related to social situations. The adaptive behavior profile for Williams syndrome involves clear strength in socialization skills (especially interpersonal skills related to initiating social interaction), strength in communication, and clear weakness in daily living skills and motor skills, relative to overall level of adaptive behavior functioning. Literature relevant to each of the components of the Williams syndrome behavioral phenotype is reviewed, including operationalizations of the Williams syndrome cognitive profile and the Williams syndrome personality profile. The sensitivity and specificity of these profiles for Williams syndrome, relative to individuals with other syndromes or mental retardation or borderline normal intelligence of unknown etiology, is considered. The adaptive behavior profile is discussed in relation to the cognitive and personality profiles. The importance of operationalizations of crucial components of the behavioral phenotype for the study of genotype/phenotype correlations in Williams syndrome is stressed. MRDD Research Reviews 2000;6:148-158.

Williams syndrome and related disorders.

Three clinical conditions displaying phenotypic overlap have been linked to mutation or deletion of the elastin gene at 7q11.23. Supravalvar aortic stenosis, an autosomal dominant disorder characterized by elastin arteriopathy, is caused by mutation or intragenic deletions of ELN resulting in loss of function. Autosomal dominant cutis laxa, a primarily cutaneous condition, is the result of frameshift mutations at ELN that cause a dominant-negative effect on elastic fiber structure. Williams syndrome, a neurodevelopmental disorder is due to a 1.5 Mb deletion that includes ELN and at least 15 contiguous genes. The disorder is characterized by dysmorphic facies, mental retardation or learning difficulties, elastin arteriopathy, a unique cognitive profile of relative strength in auditory rote memory and language and extreme weakness in visuospatial constructive cognition, and a typical personality that includes overfriendliness, anxiety, and attention problems. The understanding of these disorders has progressed from phenotypic description to identification of causative mutations and insight into pathogenetic mechanisms for some aspects of the phenotype.

Methodological issues in cross-syndrome comparisons: matching procedures, sensitivity (Se), and specificity (Sp).

We are impressed with the magnitude and potential importance of the studies presented by Sigman and Ruskin in this monograph. The within-syndrome findings for the children with autism concerning relations between early joint attention and a range of cognitive abilities a full 9 years later provide the strongest evidence so far that early nonverbal communication skills play an important role in the later development of language, intelligence, and social relations with peers. The purpose of the monograph was not limited to within-syndrome research questions, however. Sigman and Ruskin state that a major goal of the research reported in the monograph was to identify specific, unique, and universal deficits for autism and Down syndrome. They base their method of identifying such syndrome characteristics on the group-matching procedure. Given that this procedure is fraught with difficulties, we are concerned that many of Sigman and Ruskin's cross-syndrome comparisons may be incorrect. We do not mean to single out Sigman and Ruskin. The group-matching method is frequently used in special populations research, with the null hypothesis of no differences on the control variable being accepted at dangerously low p values. Our concerns with the group-matching problem extend to much of the extant research that attempts to identify characteristics of individuals based on the performance of their syndrome group relative to a control group. The profiling procedure we outlined seems more fruitful and conceptually satisfying than the traditional matching method. When profiling is not possible, however, it is important to consider the impact of CA confounds and statistical decision procedures used to ensure matching on the control variable, when interpreting syndrome differences on variables of interest.

Comparing productive vocabulary measures from the CDI and a systematic diary study.

Expressive vocabulary data gathered during a systematic diary study of one male child's early language development are compared to data that would have resulted from longitudinal administration of the MacArthur Communicative Development Inventories spoken vocabulary checklist (CDI). Comparisons are made for (1) the number of words at monthly intervals (9; 10.15 to 2; 0.15), (2) proportion of words by lexical class (i.e. noun, predicate, closed class, 'other'), (3) growth curves. The CDI underestimates the number of words in the diary study, with the underestimation increasing as vocabulary size increases. The proportion of diary study words appearing on the CDI differed as a function of lexical class. Finally, despite the differences in vocabulary size, logistic curves proved to be the best fitting model to characterize vocabulary development as measured by both the diary study and the CDI. Implications for the longitudinal use of the CDI are discussed.

Impact of intuitive theories on feature recruitment throughout the continuum of expertise.

Expertise in object domains involves both the perceptual learning of the differentiating and higher order features that are indicative of concepts and the elaboration of intuitive theories. Triad-similarity judgments, feature-salience ratings, and verbal protocols were used to investigate the effects of theories on the recruitment of features across different categorization contexts, as well as the degree to which expert categorization skills transferred to less familiar domains. Whereas novices considered features that indicated overall similarity to be more perceptually salient than were modified parts that indicated taxonomic relations, experts found them equally salient. Experts' theories were instrumental in directing feature recruitment in contexts involving identification, image generation, and similarity decisions. Experts' theories also supported the transfer of categorization skills to related, less familiar domains. The relation of mutual dependence between perceptual learning and theory development throughout the continuum of expertise is considered.

Disentangling early language development: modeling lexical and grammatical acquisition using an extension of case-study methodology.

The early lexical and grammatical development of 1 male child is examined with growth curves and dynamic-systems modeling procedures. Lexical-development described a pattern of logistic growth (R2 = .98). Lexical and plural development shared the following characteristics: Plural growth began only after a threshold was reached in vocabulary size; lexical growth slowed as plural growth increased. As plural use reached full mastery, lexical growth began again to increase. It was hypothesized that a precursor model (P. van Geert, 1991) would fit these data. Subsequent testing indicated that the precursor model, modified to incorporate brief yet intensive plural growth, provided a suitable fit. The value of the modified precursor model for the explication of processes implicated in language development is discussed.

Effects of varying levels of expertise on the basic level of categorization.

Six experiments were conducted on the effects of expertise on basic-level categorization. Individuals with varying levels of knowledge about songbirds generated lists of attributes, named objects, identified and discriminated among object silhouettes, verified category membership at 4 hierarchical levels, and visually identified songbirds primed either by species-specific, related, or unrelated birdsong. Results indicated that the original basic level never lost its privileged status. Expertise increased access to categorical information at the subordinate level for intermediate exports and at both the subordinate and sub-subordinate levels for advanced experts, causing these sublevels to function as basic. Throughout the continuum of expertise, conceptual knowledge interacted with perception. Accordingly, experts attended to different and more subtle perceptual features than novices.

Development of children's understanding of basic-subordinate inclusion relations.

Four studies focused on developmental differences in the representation of basic-subordinate inclusion relations. Tests of comprehension and production of category names, induction, and responses to direct questions pertaining to inclusion revealed a marked developmental gap between the production of subordinate category names and complete understanding of basic-subordinate inclusion relations. However, even 3-year-olds showed rudimentary knowledge of the asymmetry of inclusion. Discrepancies between children's performance on categorization tasks involving familiar and unfamiliar subordinate categories suggest that understanding of the logical nature of inclusion relations is constructed through the integration of categorical knowledge from familiar domains. Interactions among the knowledge base, pragmatic sensitivity, and information processing efficiency in the development of inclusion are discussed.

LIM-kinase1 hemizygosity implicated in impaired visuospatial constructive cognition.

To identify genes important for human cognitive development, we studied Williams syndrome (WS), a developmental disorder that includes poor visuospatial constructive cognition. Here we describe two families with a partial WS phenotype; affected members have the specific WS cognitive profile and vascular disease, but lack other WS features. Submicroscopic chromosome 7q11.23 deletions cosegregate with this phenotype in both families. DNA sequence analyses of the region affected by the smallest deletion (83.6 kb) revealed two genes, elastin (ELN) and LIM-kinase1 (LIMK1). The latter encodes a novel protein kinase with LIM domains and is strongly expressed in the brain. Because ELN mutations cause vascular disease but not cognitive abnormalities, these data implicate LIMK1 hemizygosity in imparied visuospatial constructive cognition.

Mapping the meanings of novel visual symbols by youth with moderate or severe mental retardation.

The word-learning ability of 12 school-age subjects with moderate or severe mental retardation was assessed. Subjects had little or no functional speech and used the System for Augmenting Language with visual-graphic symbols for communication. Their ability to fast map novel symbols revealed whether they possessed the novel name-nameless category (N3C) lexical operating principle. On first exposure, 7 subjects were able to map symbol meanings for novel objects. Follow-up assessments indicated that mappers retained comprehension of some of the novel words for up to delays of 15 days and generalized their knowledge to production. Ability to fast map reliably was related to symbol achievement status. Implications for understanding vocabulary acquisition by youth with mental retardation were discussed.

Acquisition of the novel name-nameless category (N3C) principle by young children who have Down syndrome.

Acquisition of the novel name-nameless category (N3C) principle by 22 children with Down syndrome between the ages of 2.42 and 3.33 years was examined to investigate the generalizability of a new approach to early lexical development: the developmental lexical principles framework. Results indicated that, as predicted, the N3C principle (operationally defined as the ability to fast map a new word to a [basic level] category), is not available at the start of lexical acquisition. The predicted link between ability to use the N3C principle and ability to perform exhaustive categorization of objects was supported. Children who used the principle had significantly larger productive vocabularies than did those who did not and, according to maternal report, had begun to acquire new words rapidly.

Early lexical acquisition and the vocabulary spurt: a response to Goldfield & Reznick.

Vocabulary development of three children (aged 1;6-1;8 at the start of the study) who had not begun to evidence a vocabulary spurt even though their productive vocabularies already included well over 50 words was followed to determine if these children eventually would have a vocabulary spurt. All three children evidenced a spurt, beginning at a mean productive vocabulary size of 112 words. The vocabulary spurt occurred at about the same time as the children first demonstrated the ability to sort objects exhaustively and to fast map new object names. Results are discussed in the context of Goldfield & Reznick's (1990; Reznick & Goldfield, 1992) argument that a substantial proportion of children never evidence a vocabulary spurt.