Early social communication in infants with fragile X syndrome and infant siblings of children with autism spectrum disorder

Research on pragmatic impairment in autistic children during the past two decades (2001-2022): hot spots and frontiers-based on CiteSpace bibliometric analysis

Pragmatic impairment has become a critical aspect of language development in autistic children and has gained significant academic attention over the past two decades. This study leverages bibliometric methods to conduct an exhaustive analysis of literature derived from Web of Science database. Utilizing CiteSpace software, we construct a knowledge map to dissect the academic hotspots in research related to pragmatic impairment in autistic children. This enables us to delineate the evolutionary trajectory of this research domain, analyze the prevailing research dimensions, and anticipate potential future dimensions. Our findings indicate that research hotspots in this field over the past two decades predominantly concentrate on assessing and diagnosing pragmatic impairment in autistic children, intervention strategies, and theory of mind. The research scope on pragmatic impairment in autistic children has progressively broadened and deepened. Research has evolved from initial descriptions and interpretations of autism to exploring the theory of mind in high-functioning, school-aged children. The current emphasis is on examining the specific skills that these children possess.

Developmental associations between motor and communication outcomes in Fragile X syndrome: Variation in the context of co-occurring autism

LAY ABSTRACT

Fragile X syndrome (FXS), the leading heritable cause of intellectual disability, has a co-occurrence rate of autism spectrum disorder (ASD) estimated at ~60%. Children with FXS experience delayed achievement and slower development of key motor abilities, which happens to an even greater extent for children with both FXS and ASD. A multitude of studies have demonstrated that motor abilities are foundational skills related to later communication outcomes in neurotypical development, as well as in the context of ASD. However, these associations remain unexamined in FXS, or FXS + ASD. In this study, we aimed to determine the associations between early motor skills and their rate of development on communication outcomes in FXS. Furthermore, we investigated whether these associations varied in the context of co-occurring FXS + ASD. Results revealed within-FXS variation in the context of co-occurring ASD between some aspects of motor development and communication outcomes, yet within-FXS consistency between others. Findings provide evidence for variability in developmental processes and outcomes in FXS in the context of co-occurring ASD and offer implications for intervention.

Differential cognitive and behavioral development from 6 to 24 months in autism and fragile X syndrome

BACKGROUND

Specifying early developmental differences among neurodevelopmental disorders with distinct etiologies is critical to improving early identification and tailored intervention during the first years of life. Recent studies have uncovered important differences between infants with fragile X syndrome (FXS) and infants with familial history of autism spectrum disorder who go on to develop autism themselves (FH-ASD), including differences in brain development and behavior. Thus far, there have been no studies longitudinally investigating differential developmental skill profiles in FXS and FH-ASD infants.

METHODS

The current study contrasted longitudinal trajectories of verbal (expressive and receptive language) and nonverbal (gross and fine motor, visual reception) skills in FXS and FH-ASD infants, compared to FH infants who did not develop ASD (FH-nonASD) and typically developing controls.

RESULTS

Infants with FXS showed delays on a nonverbal composite compared to FH-ASD (as well as FH-nonASD and control) infants as early as 6 months of age. By 12 months an ordinal pattern of scores was established between groups on all domains tested, such that controls > FH-nonASD > FH-ASD > FXS. This pattern persisted through 24 months. Cognitive level differentially influenced developmental trajectories for FXS and FH-ASD.

CONCLUSIONS

Our results demonstrate detectable group differences by 6 months between FXS and FH-ASD as well as differential trajectories on each domain throughout infancy. This work further highlights an earlier onset of global cognitive delays in FXS and, conversely, a protracted period of more slowly emerging delays in FH-ASD. Divergent neural and cognitive development in infancy between FXS and FH-ASD contributes to our understanding of important distinctions in the development and behavioral phenotype of these two groups.

Prelinguistic communication complexity predicts expressive language in initial minimally verbal autistic children

BACKGROUND

Prelinguistic communication complexity refers to the use of different communication forms such as eye gaze, gestures and vocalisations and the degree to which these forms are coordinated and how directed to a communication partner. To date, little is known about the relationship between prelinguistic communication complexity and expressive language in minimally verbal autistic children.

AIMS

To test the hypothesis that prelinguistic communication complexity predicts expressive language 12 months later in autistic children and explore whether there are any differences in specific prelinguistic intentional communicative behaviours that are related to later expressive language levels.

METHODS & PROCEDURES

This longitudinal study examined 37 minimally verbal autistic children (29-71 months old). The Communication Complexity Scale (CCS) was used to measure participants' prelinguistic communication behaviours, which were extracted from a semi-structured play interaction at Time 1. The Chinese Communicative Development Inventory (CCDI) was used to examine participants' expressive language at Time 1 and Time 2 (12 months later). According to Time 2 vocabulary size, participants were divided into two groups: Low CCDI, between 0 and 62 words, and High CCDI, more than 100 words. Linear regression was used to examine the relationship between early prelinguistic communication complexity and later expressive language. Binary logistic regression was used to determine which of the early communication behaviours were uniquely significantly related to later expressive language levels.

OUTCOMES & RESULTS

There was a significant positive relationship between prelinguistic communication complexity and expressive language 12 months later, even after controlling for age and concurrent language. Findings revealed a group difference in the frequency of gesture and vocalisation combinations between the Low and High CCDI groups at Time 1. Gesture-vocalisation combinations also predicted better expressive language levels at Time 2.

CONCLUSIONS & IMPLICATIONS

Our findings suggest that it may be beneficial to incorporate different complex communication behaviours into prelinguistic intervention targets for minimally verbal autistic children. The CCS hierarchies can be used as a reference for the intervention goals of minimally verbal autistic children. These findings highlight the importance of targeting gesture and vocalisation combinations when autistic children transition from single prelinguistic communication behaviours to multimodal behaviours.

WHAT THIS PAPER ADDS

What is already known on this subject Children use eye gaze, gestures and vocalisations to communicate with others before they learn spoken language. There is strong evidence suggest that the frequency of prelinguistic communication predicts later linguistic achievements in autistic children. However, less is known about whether prelinguistic communication complexity also predicts later language and which specific behaviours are most predictive of language outcomes. What this study adds Minimally verbal autistic children who exhibit more complex prelinguistic communication behaviours have better expressive language 12 months later. Gestures combined with vocalisations predict better expressive language in minimally verbal autistic children. What are the clinical implications of this work? When identifying intervention targets for minimally verbal autistic children, the clinicians may reference the prelinguistic communication behaviours from the CCS. The gesture and vocalisation combinations are the key behaviours when targets transit from single form to two-form behaviours.

Communication in fragile X syndrome: Patterns and implications for assessment and intervention

Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and is associated with a high rate of autism diagnosis. Language delays have been noted in the areas of overall communication and the specific areas of receptive, expressive, and pragmatic language, as well as in development of speech sounds and literacy. It has been widely noted that those individuals with a diagnosis of both FXS and autism tend to have more significant intellectual disability and language disorder. In this study, the research exploring the FXS language phenotype is presented, and the roles of cognition, autistic symptomatology, and gender are highlighted as possible. Implications for assessment and intervention approaches based on the strengths and weaknesses of the FXS language phenotype are provided.

Social communication in fragile X syndrome: pilot examination of the Brief Observation of Social Communication Change (BOSCC)

Background

Social communication is a key area of difficulty in fragile X syndrome (FXS) and there are not yet adequate outcome measurement tools. Appropriate outcome measures for FXS have been identified as a key area of research interest in order to evaluate future therapeutic trials. The Brief Observation of Social Communication Change-Minimally Verbal (BOSCC-MV), an outcome measure with strong psychometrics developed for autism spectrum disorder, has promise as an outcome measure to assess social communication change with FXS participants.

Methods

We examined the BOSCC-MV via central coders in this multi-site-trial to assess its appropriateness for FXS. Eighteen minimally verbal males ages 3–12 years were enrolled and assessed on two consecutive days and 7 participants completed a third visit 6 months later. We examined test-retest reliability, inter-rater reliability, and both convergent and divergent validity with standard clinical measures including the Autism Diagnostic and Observation Schedule-2, Vineland 3, Social Responsiveness Scale, and the Aberrant Behavior Checklist.

Results

The BOSCC-MV in FXS demonstrated strong inter-rater and test-retest reliability, comparable to previous trials in idiopathic ASD. Strong convergent validity was found with Autism Diagnostic Observation Schedule-2 and Vineland-3. Divergent validity was demonstrated between BOSCC-MV and unrelated measures.

Conclusions

The BOSCC-MV shows promise as a FXS social communication outcome measure, warranting further large-scale evaluation.

Early communication development in infants and toddlers with Fragile X syndrome

BACKGROUND AND AIMS

Individuals with fragile X syndrome (FXS) characteristically struggle with language and communication throughout the life course, but there is limited research on the development of communication before 24 months. The purpose of this study is to describe the early communication of infants and toddlers with FXS using the Communication and Symbolic Behavior Scales-Caregiver Questionnaire (CSBS-CQ), a standardized communication screening measure, as compared to the reported normative data of the CSBS-CQ and identify the percentage of infants and toddlers who scored within the range of concern. Documenting how children with FXS perform on screening measures can provide a quick snapshot of skills to help clinicians determine the need for services.

METHODS

Participants were 22 infants and toddlers with FXS between 6 and 29 months. Performance on the CSBS-CQ was compared to the measure's normative data. The CSBS-CQ was completed by mothers, and children were administered the Mullen Scales of Early Learning. Because co-occurring autism is common in FXS, the presence of autism was determined using a clinical best estimate procedure.

RESULTS

Overall and within the domains and subdomains of the CSBS-CQ, infants and toddlers with FXS had significantly lower scores than the normative data. Further, 68.2% of our sample was in the range of concern for their overall communication score. The presence of autism led to consistently lower scores, and more infants and toddlers with FXS + autism scored within the range of concern.

CONCLUSIONS

Our findings suggest that delays in early communication are evident in comparison to typically developing norms before 24 months. These findings also emphasize that infants and toddlers with FXS would likely benefit from early language intervention given that 68.2% of our sample was in the range of concern for their overall communication score.

IMPLICATIONS

Early identification and developmental monitoring of children with FXS will help to determine concerns in communication and other domains of development. While early communication broadly may not be an early indicator of autism in FXS, some specific skills, such as eye gaze, may serve as such an indicator. Screening measures, like the CSBS-CQ, may help monitor both early communication impairments and autism symptoms. Infants and toddlers with FXS, regardless of autism status, will benefit from early language interventions.

The development of early social cognitive skills in neurogenetic syndromes associated with autism: Cornelia de Lange, fragile X and Rubinstein-Taybi syndromes

BACKGROUND

Cornelia de Lange (CdLS), Fragile X (FXS) and Rubinstein-Taybi syndromes (RTS) evidence unique profiles of autistic characteristics. To delineate these profiles further, the development of early social cognitive abilities in children with CdLS, FXS and RTS was compared to that observed in typically developing (TD) and autistic (AUT) children.

METHODS

Children with CdLS (N = 22), FXS (N = 19) and RTS (N = 18), completed the Early Social Cognition Scale (ESCogS). Extant data from AUT (N = 19) and TD (N = 86) children were used for comparison.

RESULTS

Similar to AUT children, children with CdLS, FXS and RTS showed an overall delay in passing ESCogS tasks. Children with CdLS showed a similar degree of delay to AUT children and greater delay than children with FXS and RTS. The CdLS, FXS and RTS groups did not pass tasks in the same sequence observed in TD and AUT children. Children with CdLS (p = 0.04), FXS (p = 0.02) and RTS (p = 0.04) performed better on tasks requiring understanding simple intentions in others significantly more than tasks requiring joint attention skills.

CONCLUSIONS

An underlying mechanism other than general cognitive delay may be disrupting early social cognitive development in children with CdLS, FXS and RTS. Factors that may disrupt early social cognitive development within these syndromes are discussed.

Motor Influences on Communication: Comparisons Between Down Syndrome and Fragile X Syndrome

Motor skills, an important foundation for language and communication, are considerably delayed in children with Down syndrome (DS) and fragile X syndrome (FXS). However, the impact of these impairments on expressive and receptive communication and the phenotypic specificity of these associations remains unknown. Participants included 37 with DS and 37 age and developmentally matched children with FXS. Syndrome-specific motor and communication profiles emerged, with higher communication scores seen in the DS versus FXS on, but lower gross motor scores. Significant associations between domains of motor and communication were identified for both groups with additional phenotype-specific patterns. Findings demonstrate the importance of early motor abilities for communication in DS and FXS. Implications for phenotypic specificity and targeted intervention are discussed.

Characterizing the Richness of Maternal Input for Word Learning in Neurogenetic Disorders

Promoting language abilities, including early word learning, in children with neurogenetic disorders with associated language disorders, such as Down syndrome (DS) and fragile X syndrome (FXS), is a main concern for caregivers and clinicians. For typically developing children, the quality and quantity of maternal language input and maternal gesture use contributes to child word learning, and a similar relation is likely present in DS and FXS. However, few studies have examined the combined effect of maternal language input and maternal gesture use on child word learning. We present a multidimensional approach for coding word-referent transparency in naturally occurring input to children with neurogenetic disorders. We conceptualize high-quality input from a multidimensional perspective, considering features from linguistic, interactive, and conceptual dimensions simultaneously. Using case examples, we highlight how infrequent the moments of word-referent transparency are for three toddlers with DS during play with their mothers. We discuss the implications of this multidimensional framework for children with DS and FXS, including the clinical application of our approach to promote early word learning for these children.

Early behavioral and physiological markers of social anxiety in infants with fragile X syndrome

Background

Social anxiety is highly prevalent in neurotypical children and children with fragile X syndrome (FXS). FXS is a genetic syndrome that is characterized by intellectual disability and an increased risk for autism spectrum disorder. If social anxiety is left untreated, negative outcomes are highly prevalent later in life. However, early detection of social anxiety is challenging as symptoms are often subtle or absent very early in life. Given the prevalence and impairment associated with childhood social anxiety, efforts have accelerated to identify risk markers of anxiety. A cluster of early features of anxiety have been identified including elevated behavioral inhibition, attentional biases, and physiological dysregulation that index early emerging markers of social anxiety. Infants with FXS provide a unique opportunity to study the earlier predictors of social anxiety. The current study utilized a multi-method approach to investigate early markers of social anxiety in 12-month-old infants with FXS.

Method

Participants included 32 infants with FXS and 41 low-risk controls, all approximately 12 months old. Parent-reported social behavioral inhibition was recorded from the Infant Behavior Questionnaire (IBQ-R). Direct observations of behavioral inhibition and attention were measured during a stranger approach task with respiratory sinus arrhythmia collected simultaneously.

Results

Parent-reported social behavioral inhibition was not significantly different between groups. In contrast, direct observations suggested that infants with FXS displayed elevated behavioral inhibition, increased attention towards the stranger, and a blunted respiratory sinus arrhythmia response.

Conclusions

Findings suggest that infants with FXS show both behavioral and physiological markers of social anxiety at 12 months old using a biobehavioral approach with multiple sources of input. Results highlight the importance of a multi-method approach to understanding the complex early emergent characteristics of anxiety in infants with FXS.

Measuring Change in the Communication Skills of Children With Austim Spectrum Disorder Using the Communication Complexity Scale

Changes in minimal verbal communication by children with autism spectrum disorder (ASD) were measured with the Communication Complexity Scale (CCS) and other communication assessments. The CCS measures complexity of preverbal and beginning verbal communication used to communicate behavior regulation and joint attention. The purpose was to investigate if the CCS was responsive to changes associated with a behavioral intervention aimed at improving communication skills. Changes were detected with CCS scores, rates of initiating joint attention, and the Mullen Scales of Early Learning (MSEL) Expressive Language subscale. Significant changes in CCS scores were also detected for a subgroup of participants who did not show significant changes on the MSEL Expressive Language subscale, demonstrating that CCS scores are sensitive to changes associated with a behavioral intervention.

Linking risk factors and outcomes in autism spectrum disorder: is there evidence for resilience?

Autism spectrum disorder (referred to here as autism) is one of several overlapping neurodevelopmental conditions that have variable impacts on different individuals. This variability results from dynamic interactions between biological and non-biological risk factors, which result in increasing differentiation between individuals over time. Although this differentiation continues well into adulthood, the infancy period is when the brain and behavior develop rapidly, and when the first signs and symptoms of autism emerge. This review discusses advances in our understanding of the causal pathways leading to autism and overlapping neurodevelopmental conditions. Research is also mapping trajectories of brain and behavioral development for some risk groups, namely later born siblings of children with autism and/or infants referred because of developmental concerns. This knowledge has been useful in improving early identification and establishing the feasibility of targeted interventions for infant risk groups before symptoms arise. However, key knowledge gaps remain, such as the discovery of protective factors (biological or environmental) that may mitigate the impact of risk. Also, the dynamic mechanisms that underlie the associations between risk factors and outcomes need further research. These include the processes of resilience, which may explain why some individuals at risk for autism achieve better than expected outcomes. Bridging these knowledge gaps would help to provide tools for early identification and intervention that reflect dynamic developmental pathways from risk to outcomes.

Preverbal Communication Complexity in Infants

The development of prelinguistic communication in typically developing infants is marked by changes in complexity as well as frequency, yet most measures focus on frequency. In the current study we used the Communication Complexity Scale (CCS) to measure prelinguistic complexity of typically developing infants in a cross-sectional sample of 6-, 8-, 10- and 12-month-olds (N = 204) during semi-structured play interaction. For each toy/interactive episode, infants' highest level of communication complexity (ranging from 0 for no response to 12 for multi-word verbalization), for both joint attention (i.e., social) and behavior regulation (e.g., requesting) functions, was scored. In addition, the same interaction was coded for frequency of all prelinguistic communication acts. Results of multivariate models indicated age-related differences in prelinguistic complexity. Measures of prelinguistic complexity and frequency evidenced moderate to strong correlations, with age-related differences by function (joint attention and behavior regulation). Significant associations with parent-report communication questionnaires were observed for both complexity and frequency measures. Results indicate that evaluating complexity of infant preverbal communication skill with the CCS is a valuable approach that can meaningfully index developmental differences in prelinguistic and early linguistic communication.

Task and Participant Variables Predict Communication Complexity Scale (CCS) Scores: Closer Examination of the CCS

Communication Complexity Scale (CCS) scores for 269 minimally verbal participants were examined to determine if communicator behavior and task and communicator characteristics were related to scores in a manner consistent with theoretical and research evidence expectations. Each participant completed an interactive assessment with 6 joint attention tasks and 6 behavior regulation tasks. Caregivers completed the Vineland Adaptive Behavior Scales II. Results indicated (a) joint attention tasks yielded lower scores than behavior regulation tasks, (b) older participants had lower scores, (c) individuals with autism spectrum disorder scored more similarly than those without, (d) the difference between joint attention and behavior regulation scores was greater for the autism spectrum disorder group, and (e) adaptive behavior was significantly positively related to complexity scores.

Gesture Frequency and Function in Infants With Fragile X Syndrome and Infant Siblings of Children With Autism Spectrum Disorder

Purpose Infant siblings of children with autism spectrum disorder (ASIBs) and infants with fragile X syndrome (FXS) are both at risk for developing autism spectrum disorder (ASD) and communication disorders; however, very few studies have examined 1 of the earliest forms of intentional communication in infants from these groups: gestures. This study examined the frequency and function of gesture use across 12-month-old infant ASIBs, infants with FXS, and low-risk controls. Method Participants included 23 ASIBs who did not later meet diagnostic criteria for ASD, 18 infants with FXS, and 21 low-risk controls. Gestures were coded from a semistructured play-based interaction. Results Overall, infants with FXS displayed fewer gestures than low-risk infants, whereas ASIBs did not differ from the FXS or low-risk groups in overall gesture frequency. In terms of the communicative function of the gestures used, the FXS and ASIB groups displayed significantly fewer social interaction gestures than the low-risk controls, with large effect sizes. Conclusion This study contributes to scant knowledge of early communication phenotypes of infant ASIBs who do not meet criteria for ASD and infants with FXS. Results indicated that gesture function, not frequency, best discriminated at-risk infants from low-risk infants at 12 months of age. Findings have implications for the clinical evaluation and treatment of infants at high risk for ASD and communication disorders.

Infant Social Avoidance Predicts Autism but Not Anxiety in Fragile X Syndrome

Objective: Autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and anxiety are three of the most common childhood psychiatric disorders. Early trajectories of social avoidance have been linked with these psychiatric disorders in previous studies, but it remains unclear how social avoidance differentially predicts comorbid disorders in a high-risk genetic subgroup. Here, we delineate the association between trajectories of social avoidance from infancy and subsequent ASD, ADHD, and anxiety outcomes at preschool in children with fragile X syndrome (FXS), a well-characterized single-gene disorder highly associated with social avoidance as well as elevated rates of ASD, ADHD, and anxiety. Method: Males with FXS (n = 78) aged 4-62 months participated in a longitudinal study resulting in 201 assessments. The Social Avoidance Scale (SAS) documented socially avoidant behaviors from infancy in three domains-physical movement, facial expression, and eye contact during both the first minute and the last hour of an interaction. ASD, ADHD, and anxiety symptom outcomes at preschool were measured via parent-report questionnaires. Results: Increased social avoidance across infancy and preschool predicted elevated ASD symptom severity but reduced ADHD and anxiety symptom severity in males with FXS. Conclusion: ASD, ADHD, and anxiety symptoms relate inconsistently to social avoidance behaviors, providing new insight toward the debate of independence or overlap among these disorders in FXS and other disorders (i.e., ASD). The results suggest that the nuanced profile of the developmental and temporal aspects of social avoidance may inform more the accuracy of differential diagnoses of comorbid psychiatric disorders in FXS.

Application of the Communication Complexity Scale in Peer and Adult Assessment Contexts for Preschoolers With Autism Spectrum Disorders

Purpose The purpose of this study was to measure changes in communication of preschoolers with autism using the Communication Complexity Scale (CCS; Brady et al., 2012 ) and to examine the utility of the CCS in measuring pretreatment and posttreatment changes within peer and adult assessment contexts. Method The CCS was used to code preassessment and postassessment for 23 children with autism randomly assigned to a treatment that incorporated a peer-mediated approach and a speech-generating device and 22 assigned to a business-as-usual condition with untrained peers. Children were assessed in 2 structured 30-min contexts-1 with an adult examiner and 1 with a peer partner coached by an adult. Results Children in both groups showed significant changes in communication complexity CCS scores from pretreatment to posttreatment in the adult and peer contexts. At both occasions, CCS scores were higher with adult partners yet showed greater improvements over time with peer partners. Conclusions Results showed that the CCS was sensitive to change over time but did not discriminate changes in communication complexity associated with maturation versus treatment. It did show some differences based on interactions with peer versus adult partners. Outcomes provide preliminary support for using this scale to measure communication changes in different contexts. Supplemental Material https://doi.org/10.23641/asha.7408856.

Stability of core language skill from infancy to adolescence in typical and atypical development

Command of language is a fundamental life skill, a cornerstone of cognitive and socioemotional development, and a necessary ingredient for successful functioning in society. We used 15-year prospective longitudinal data from the Avon Longitudinal Study of Parents and Children to evaluate two types of stability of core language skill in 5036 typically developing and 1056 atypically developing (preterm, dyslexic, autistic, and hearing impaired) children in a multiage, multidomain, multimeasure, multireporter framework. A single core language skill was extracted from multiple measures at multiple ages, and this skill proved stable from infancy to adolescence in all groups, even accounting for child nonverbal intelligence and sociability and maternal age and education. Language skill is a highly conserved and robust individual-differences characteristic. Lagging language skills, a risk factor in child development, would profitably be addressed early in life.

Initiating joint attention use in infants at high-risk for autism spectrum disorder

BACKGROUND

Impairment in initiating joint attention (IJA) is associated with autism spectrum disorder (ASD) in children, although it is unclear when impairments arise. Due to the early development of IJA use and late diagnosis of ASD, groups at high-risk of ASD, such as infants with an older sibling with ASD (ASIBs) and infants with fragile X syndrome (FXS), provide opportunities to study early IJA behaviours for children who are later diagnosed with ASD. This study analysed these two groups to determine if IJA use differed compared with typically developing (TD) peers at 12 months and whether IJA was associated with later ASD outcomes.

METHOD

An experimental attention task was used to analyse IJA gaze shifts and gestures in the high-risk groups. Clinical best estimate diagnoses were given to each participant to compare IJA behaviours to ASD severity.

RESULTS

No differences in the frequency of IJA gaze shifts and gestures were found between 12-month-old ASIBs and TD controls, but infants with FXS demonstrated a significantly reduced range of IJA gaze shifts relative to TD controls. Additionally, ASD outcomes at 24 months were related to IJA use for infants with FXS at 12 months, but not infant ASIBs, although these findings were explained by differences in nonverbal cognitive development.

CONCLUSIONS

Although previous studies have reported delays in IJA use in children with FXS and ASIBs at ages 21 and 14 months, respectively, our results suggest IJA behaviours for these high-risk groups are not distinct from TD children at 12 months. When differences were found at 12 months, they were explained by nonverbal cognitive development, particularly for infants with FXS. Differences in IJA use at 12 months in this study were too small to serve as a potential indicator of later ASD.

Early gesture use in fragile X syndrome

BACKGROUND

Emerging evidence suggests that children with fragile X syndrome (FXS) exhibit abnormal gesture use early in development, although few studies have investigated the emergence of gesture use in this population or the impact of autism spectrum disorder (ASD) features on these behaviours. The present study examined the longitudinal development of gesture use in infants with FXS relative to low-risk controls and infant siblings of children with ASD (high-risk siblings), with the goal of establishing potentially unique patterns of gesture development in infants with FXS and understanding the relative impact of ASD symptom severity on these patterns.

METHOD

Participants included 86 male infants (39 FXS, 27 high-risk siblings and 20 low-risk infants) assessed at 9, 12 and 24 months of age. Multilevel modelling was used to assess differences in number of gestures used and rates of gesture use across groups, as well as the relative impact of ASD symptom severity and nonverbal skills on these patterns.

RESULTS

Infants with FXS used fewer gestures than high-risk siblings and low-risk infants, with this difference being primarily accounted for by the effect of low nonverbal abilities in the FXS group. Furthermore, although higher ASD symptom severity was associated with the use of fewer gestures in both the FXS and high-risk sibling groups, a significant amount of variance was shared between ASD symptom severity and nonverbal skills in FXS, but not in high-risk siblings.

CONCLUSIONS

This study presents the first longitudinal analysis of early gesture development in FXS by using a multigroup design, clarifying the relative roles of cognitive deficits and ASD symptom severity in the development of gesture use in FXS. These findings offer novel evidence that early gesture use in FXS may reflect broader features of the FXS phenotype rather than predicting later social-communicative deficits characteristic of comorbid ASD.