Executive function and theory of mind performance of boys with fragile-X syndrome

Relations between Everyday Executive Functioning and Language in Youth with Down Syndrome and Youth with Autism Spectrum Disorder

Language and executive functioning are major impairments in many neurodevelopmental disorders, but little is known about the relations between these constructs, particularly using parent-report. Thus, the current research sought to examine relations between executive function and language in two groups - Down syndrome (DS; n=41; Mage = 11.2) and autism spectrum disorder (ASD; n=91; Mage = 7.7). Results were as follows: in DS, executive function predicted pragmatic, but not structural language after covarying for age, sex, and social functioning; in ASD, executive function predicted both. Findings highlight the interrelatedness of language and executive functioning and may have implications for intervention development.

Language processing skills linked to FMR1 variation: A study of gaze-language coordination during rapid automatized naming among women with the FMR1 premutation

The FMR1 premutation (PM) is relatively common in the general population. Evidence suggests that PM carriers may exhibit subtle differences in specific cognitive and language abilities. This study examined potential mechanisms underlying such differences through the study of gaze and language coordination during a language processing task (rapid automatized naming; RAN) among female carriers of the FMR1 PM. RAN taps a complex set of underlying neuropsychological mechanisms, with breakdowns implicating processing disruptions in fundamental skills that support higher order language and executive functions, making RAN (and analysis of gaze/language coordination during RAN) a potentially powerful paradigm for revealing the phenotypic expression of the FMR1 PM. Forty-eight PM carriers and 56 controls completed RAN on an eye tracker, where they serially named arrays of numbers, letters, colors, and objects. Findings revealed a pattern of inefficient language processing in the PM group, including a greater number of eye fixations (namely, visual regressions) and reduced eye-voice span (i.e., the eyes' lead over the voice) relative to controls. Differences were driven by performance in the latter half of the RAN arrays, when working memory and processing load are the greatest, implicating executive skills. RAN deficits were associated with broader social-communicative difficulties among PM carriers, and with FMR1-related molecular genetic variation (higher CGG repeat length, lower activation ratio, and increased levels of the fragile X mental retardation protein; FMRP). Findings contribute to an understanding of the neurocognitive profile of PM carriers and indicate specific gene-behavior associations that implicate the role of the FMR1 gene in language-related processes.

Executive Function in Fragile X Syndrome: A Systematic Review

Executive function (EF) supports goal-directed behavior and includes key aspects such as working memory, inhibitory control, cognitive flexibility, attention, processing speed, and planning. Fragile X syndrome (FXS) is the leading inherited monogenic cause of intellectual disability and is phenotypically characterized by EF deficits beyond what is expected given general cognitive impairments. Yet, a systematic review of behavioral studies using performance-based measures is needed to provide a summary of EF deficits across domains in males and females with FXS, discuss clinical and biological correlates of these EF deficits, identify critical limitations in available research, and offer suggestions for future studies in this area. Ultimately, this review aims to advance our understanding of the underlying pathophysiological mechanisms contributing to EF in FXS and to inform the development of outcome measures of EF and identification of new treatment targets in FXS.

Developmental trajectories of executive functions in young males with fragile X syndrome

BACKGROUND

Executive functions (EF) have been identified as impaired in FXS, but few studies have examined their developmental trajectories.

AIMS

The primary aim of this longitudinal study was to examine the development of EF in young males with FXS compared to Mental Age (MA)-matched controls.

METHODS AND PROCEDURES

The sample comprised 56 boys with FXS (ages 7-13 years), and 48 MA-matched typical boys (ages 4-8 years). EF tasks included measures of inhibitory control, working memory, cognitive flexibility/set-shifting, problem solving/planning, and processing speed. Tasks were administered at three time points over five-years.

OUTCOMES AND RESULTS

The MA-Matched Typical boys significantly outperformed the FXS boys on all EF tasks, with the FXS Group showing a pattern of slow, but positive growth on most EF tasks. For working memory tasks, significant interactions were noted between MA and autism symptom severity, and MA and medication status. The probability of task completion increased with higher MA.

CONCLUSIONS AND IMPLICATIONS

These findings contribute to our understanding of the development of EF in this population. They also lay the foundation for use of EF tasks in treatment efforts, particularly with respect to documenting improvements and practice effects, and in understanding associations with targeted developmental outcomes.

A Duck Wearing Boots?! Pragmatic Language Strategies for Repairing Communication Breakdowns Across Genetically Based Neurodevelopmental Disabilities

PURPOSE

The ability to repair breakdowns in communication is an important pragmatic language skill that helps to maintain clear and meaningful interactions. Examining this ability in genetically based neurodevelopmental disabilities in which pragmatics are affected can provide important information about the precise pragmatic skills impacted across different populations and also help to identify core mechanisms underlying pragmatic impairment that may inform tailored interventions.

METHOD

Individuals with idiopathic autism spectrum disorder (ASD-O; n = 40), fragile X syndrome with comorbid autism spectrum disorder (FXS-ASD; n = 62), FXS without ASD (FXS-O; n = 38), Down syndrome (DS; n = 43), and typical development (TD; n = 42) completed a picture description task in which an examiner prompted for clarification repeatedly to elicit communication repair attempts. Participants' response strategies were compared across diagnostic groups and by sex and examined in relationship to different cognitive abilities.

RESULTS

Relatively few group differences were observed in responses to requests for clarification overall. Males with ASD-O responded less to clarification requests than males with FXS-ASD and FXS-O, and males with FXS-ASD responded more inappropriately than males with ASD-O and DS. All male groups became less responsive to prompts for communication repair across the series of requests. Males with TD and FXS-ASD used less effective strategies than females.

CONCLUSION

All groups showed some proficiency in repairing communication breakdowns, although individuals with ASD-O and FXS-ASD demonstrated some key areas of difficulty, highlighting the importance of considering ASD symptomatology in assessment and treatment of males with FXS. Findings also suggest that, across groups, multiple requests for clarification may lead to disengagement from the interaction. Finally, correlated skills observed across groups could implicate different underlying skills related to communication repair abilities across groups.

Overview of Social Cognitive Dysfunctions in Rare Developmental Syndromes With Psychiatric Phenotype

Rare neurodevelopmental syndromes often present social cognitive deficits that may underlie difficulties in social interactions and increase the risk of psychosis or autism spectrum disorders. However, little is known regarding the specificities of social cognitive impairment across syndromes while it remains a major challenge for the care. Our review provides an overview of social cognitive dysfunctions in rare diseases associated with psychiatric symptoms (with a prevalence estimated between 1 in 1,200 and 1 in 25,000 live births: 22q11.2 deletion syndrome, Angelman syndrome, Fragile X syndrome, Klinefelter syndrome, Prader-Willi syndrome, Rett syndrome, Smith-Magenis syndrome, Turner syndrome, and Williams syndrome) and shed some light on the specific mechanisms that may underlie these skills in each clinical presentation. We first detail the different processes included in the generic expression "social cognition" before summarizing the genotype, psychiatric phenotype, and non-social cognitive profile in each syndrome. Then, we offer a systematic review of the social cognitive abilities and the disturbed mechanisms they are likely associated with. We followed the PRISMA process, including the definition of the relevant search terms, the selection of studies based on clear inclusion, and exclusion criteria and the quality appraisal of papers. We finally provide insights that may have considerable influence on the development of adapted therapeutic interventions such as social cognitive training (SCT) therapies specifically designed to target the psychiatric phenotype. The results of this review suggest that social cognition impairments share some similarities across syndromes. We propose that social cognitive impairments are strongly involved in behavioral symptoms regardless of the overall cognitive level measured by intelligence quotient. Better understanding the mechanisms underlying impaired social cognition may lead to adapt therapeutic interventions. The studies targeting social cognition processes offer new thoughts about the development of specific cognitive training programs, as they highlight the importance of connecting neurocognitive and SCT techniques.

Joint Attention and Early Social Developmental Cascades in Neurogenetic Disorders

This review examines what is known about joint attention and early social development in three neurogenetic syndromes: Down syndrome, Williams syndrome, and fragile X syndrome. In addition, the potential cascading effects of joint attention on subsequent social development, especially social interaction and social cognition are proposed. The potential issues and complexities associated with conducting prospective, longitudinal studies of infant social development in neurogenetic disorders are discussed.

Negative life events predict performance on an executive function task in young adults with developmental disabilities

BACKGROUND

Recent research with typically developing children indicates that chronic stress can be detrimental to the development of executive function. This study extends this work to individuals with developmental disabilities and examines the longitudinal relationship between an indicator of chronic stress, negative life events, and performance on a task of executive function within a group of 30 individuals with early identified developmental disabilities.

METHODS

Multilevel modelling was used to analyse the relationship between cumulative negative life events and response time on a Flanker task.

RESULTS

As hypothesized, individuals who had experienced more cumulative negative life events in their families demonstrated longer response time, an indicator of less efficient executive function.

CONCLUSIONS

The association between cumulative negative life events and executive function for children with developmental disabilities suggests the prominent role of the environment for development in this domain. These findings also suggest the importance of providing services, resources, and interventions that will help families adaptively cope with stressful circumstances.

Early mastery motivation as a predictor of executive function in young adults with developmental disabilities

The role of early childhood mastery motivation as a predictor of executive function 20 years later was examined in a sample of 39 individuals who had early diagnosed developmental disabilities. Multilevel modeling was used to analyze predictors of accuracy and response time on a Flanker task measuring executive function. As predicted, participants had relatively poorer performance on trials requiring inhibition and rule switches. Individuals with Down syndrome, in comparison to other participants, demonstrated longer response times. Young adults who had higher levels of persistence on mastery motivation tasks during early childhood displayed higher levels of accuracy and shorter response times on the executive function task. Possible mechanisms by which early mastery motivation relates to later executive function are discussed.

Cognitive aspects of Fragile X syndrome

Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability. It is primarily caused by the expansion of a CGG trinucleodide repeat located in the 5' untranslated region of the X-linked FMR1 gene. Individuals with FXS present with variable intellectual quotients (IQs) ranging from the average to the severe intellectual disability level. A range of neurocognitive strengths and challenges are observed in individuals with FXS. This article provides an overview of our current understanding related to cognition and FXS. Cognitive functioning levels, profiles, and IQ trajectories are discussed. Limitations of existing neuropsychological measures are described. WIREs Cogn Sci 2014, 5:501-508. doi: 10.1002/wcs.1296 This article is categorized under: Neuroscience > Cognition.

Social approach and emotion recognition in fragile X syndrome

Evidence is emerging that individuals with Fragile X syndrome (FXS) display emotion recognition deficits, which may contribute to their significant social difficulties. The current study investigated the emotion recognition abilities, and social approachability judgments, of FXS individuals when processing emotional stimuli. Relative to chronological age- (CA-) and mental age- (MA-) matched controls, the FXS group performed significantly more poorly on the emotion recognition tasks, and displayed a bias towards detecting negative emotions. Moreover, after controlling for emotion recognition deficits, the FXS group displayed significantly reduced ratings of social approachability. These findings suggest that a social anxiety pattern, rather than poor socioemotional processing, may best explain the social avoidance observed in FXS.

Emotion recognition and visual-scan paths in Fragile X syndrome

This study investigated emotion recognition abilities and visual scanning of emotional faces in 16 Fragile X syndrome (FXS) individuals compared to 16 chronological-age and 16 mental-age matched controls. The relationships between emotion recognition, visual scan-paths and symptoms of social anxiety, schizotypy and autism were also explored. Results indicated that, compared to both control groups, the FXS group displayed specific emotion recognition deficits for angry and neutral (but not happy or fearful) facial expressions. Despite these evident emotion recognition deficits, the visual scanning of emotional faces was found to be at developmentally appropriate levels in the FXS group. Significant relationships were also observed between visual scan-paths, emotion recognition performance and symptomology in the FXS group.

Outcome measures for clinical trials in fragile X syndrome

OBJECTIVE

Progress in basic neuroscience has led to identification of molecular targets for treatment in fragile X syndrome (FXS) and other neurodevelopmental disorders; however, there is a gap in translation to targeted therapies in humans. One major obstacle to the demonstration of efficacy in human trials has been the lack of generally accepted endpoints to assess improvement in function in individuals with FXS. To address this problem, the National Institutes of Health convened a meeting of leading scientists and clinicians with the goal of identifying and standardizing outcome measures for use as potential endpoints in clinical trials in FXS.

METHODS

Participants in the meeting included FXS experts, experts in the design and implementation of clinical trials and measure development, and representatives from advocacy groups, industry, and federal agencies.

RESULTS

The group generated recommendations for optimal outcome measures in cognitive, behavioral, and biomarker/medical domains, including additional testing and validation of existing measures and development of new measures in areas of need. Although no one endpoint or set of endpoints could be identified that met all criteria as an optimal measure, recommendations are presented in this report.

CONCLUSION

The report is expected to guide the selection of measures in clinical trials and lead to the use of a more consistent battery of measures across trials. Furthermore, this will help to direct research toward gaps in the development of validated FXS-specific outcome measures and to assist with interpretation of clinical trial data by creating templates for measurement of treatment efficacy.

Behavioural phenotypes and special educational needs: is aetiology important in the classroom?

BACKGROUND

A number of genetic conditions with associated intellectual disability and/or special educational needs have increasingly well-defined behavioural phenotypes. Thus, the concept of 'behavioural phenotype' and aetiology of intellectual disability may be important with regard to school-based interventions.

METHOD

The evidence for distinctive cognitive and behavioural aspects of five of the most common genetic syndromes (Down syndrome, fragile X syndrome, Williams syndrome, Prader-Willi syndrome and velo-cardio-facial syndrome) associated with special educational needs is reviewed with respect to key studies and findings. The possible utility of aetiology-related interventions in education is discussed with reference to arguments for and against such approaches with respect to published guidelines and published research.

RESULTS

Behavioural phenotypes are probabilistic and many children with a specific genetic syndrome will share commonalities with other children with other genetic syndromes and within syndrome variability is not uncommon. There is evidence that teachers and parents have limited knowledge of aspects of the proposed cognitive and behaviour profiles associated with the reviewed syndromes. While there are published guidelines in the area of learning and behaviour for each of the five reviewed syndromes there is a limited amount of evidence of the efficacy of such approaches in school settings.

CONCLUSION

It is likely that knowing the aetiology of a child's special educational needs will be helpful for staff who work in school settings in relation to cognitive and behavioural implications. However, how such knowledge might inform teaching practice or behavioural interventions has not been studied. A model is proposed that might help inform educators about the possible role of aetiology in the classroom.

Event-related potential alterations in fragile X syndrome

Fragile X Syndrome (FXS) is the most common form of X-linked intellectual disability (ID), associated with a wide range of cognitive and behavioral impairments. FXS is caused by a trinucleotide repeat expansion in the FMR1 gene located on the X-chromosome. FMR1 is expected to prevent the expression of the "fragile X mental retardation protein (FMRP)", which results in altered structural and functional development of the synapse, including a loss of synaptic plasticity. This review aims to unveil the contribution of electrophysiological signal studies for the understanding of the information processing impairments in FXS patients. We discuss relevant event-related potential (ERP) studies conducted with full mutation FXS patients and clinical populations sharing symptoms with FXS in a developmental perspective. Specific deviances found in FXS ERP profiles are described. Alterations are reported in N1, P2, Mismatch Negativity (MMN), N2, and P3 components in FXS compared to healthy controls. Particularly, deviances in N1 and P2 amplitude seem to be specific to FXS. The presented results suggest a cascade of impaired information processes that are in line with symptoms and anatomical findings in FXS.

Social communication and theory of mind in boys with autism and fragile x syndrome

Impairments in the social use of language, or pragmatics, constitute a core characteristic of autism. Problems with pragmatic language have also been documented in fragile X syndrome (FXS), a monogenic condition that is the most common known genetic cause of autism. Evidence suggests that social cognitive ability, or theory of mind, may also be impaired in both conditions, and in autism, may importantly relate to pragmatic language ability. Given the substantial overlap observed in autism and FXS, this study aimed to better define those social-communicative phenotypes that overlap in these two conditions by comparing pragmatic language ability and theory of mind in children with idiopathic autism and children with FXS, with and without autism, as well as children with Down syndrome and typically developing controls. We further examined correlations between these cognitive-behavioral phenotypes and molecular genetic variation related to the Fragile X Mental Retardation-1 gene (FMR1) in the FXS group. Results indicated that children with idiopathic autism and those with FXS and autism performed comparably on direct-assessment measures of pragmatic language and theory of mind, whereas those with FXS only did not differ from controls. Theory of mind was related to pragmatic language ability in all groups. Pragmatic language and theory of mind also correlated with genetic variation at the FMR1 locus (Cytosine-Guanine-Guanine repeats and percent methylation). These results point toward substantial overlap in the social and language phenotypes in autism and FXS and suggest a molecular genetic basis to these phenotypic profiles.

Fragile X syndrome: lifespan developmental implications for those without as well as with intellectual disability

PURPOSE OF REVIEW

Advances in developmental neuropsychiatry and the mental health needs of people with intellectual disability are creating ever greater understanding of the critical associations between human genome variations and psychological functioning throughout lifespan and across the entire intellectual ability spectrum. This review highlights the recent developments and their clinical implications for people with fragile X syndrome.

RECENT FINDINGS

There is substantial evidence for individuals of all ages and intellectual abilities being prone to psychological profiles determined not only by having a fragile X gene full mutation, but also by having premutations and intermediate alleles. The importance of these genetic contributors to mental life, if anything, increases with age. Premutation carriers are prone to neurodegenerative mid-life fragile X tremor-ataxia syndrome. Women with premutations experience premature ovarian insufficiency. Imbalances in the (gamma amino butyrie acid)-glutamate mediated postsynaptic cascade central neuronal pathways are a current focus of psychopharmacological enquiry, giving the hope of syndrome-specific medical treatments.

SUMMARY

Findings from genetic, neurological, biochemical, psychological and pharmacological research are combining to revolutionize understanding of the pathogenesis of developmental and psychological disabilities affecting individuals with fragile X syndrome irrespective of age, intelligence level and gene mutation status. Results of syndrome-specific medication trials are awaited.

Executive functions in individuals with Williams syndrome

BACKGROUND

The present study was aimed at investigating working memory (WM) and executive functions capacities in individuals with Williams syndrome (WS) as compared with mental-age matched typically developing (TD) children.

METHOD

In order to serve the study goal, a sizeable battery of tasks tapping WM as well as attention, memory, planning, categorisation, shifting and inhibition abilities was administered to 15 individuals with WS (mean chronological age of 19.11 and mean mental age of 6.10), and to a group of 15 TD children (mean chronological age of 7.6 and mean mental age of 6.9).

RESULTS

Participants with WS showed deficits in both verbal and visual-spatial modalities for selective and sustained attention, short-term memory and WM, planning and inhibition. However, considering categorisation and shifting abilities, relatively unimpaired performance emerged on those tasks relying on verbal materials.

CONCLUSIONS

These findings are both relevant to improve our knowledge about certain qualitative aspects of the anomalous cognitive development in WS as well as for its eventual clinical implications.

Whole-brain expression analysis of FMRP in adult monkey and its relationship to cognitive deficits in fragile X syndrome

Fragile X syndrome (FXS) is one of the most prevalent forms of heritable mental retardation and developmental delay in males. The syndrome is caused by the silencing of a single gene (fragile X mental retardation-1; FMR1) and the lack of expression of its protein product (fragile X mental retardation-1 protein; FMRP). Recent work has linked the high expression levels of FMRP in the magnocellular layers of lateral geniculate nucleus (M-LGN) of the visual system to a specific reduction of perceptual function known to be mediated by that neural structure. This finding has given rise to the intriguing notion that FMRP expression level may be used as an index of susceptibility of specific brain regions to the observed perceptual and cognitive deficits in FXS. We undertook a comprehensive expression profiling study of FMRP in the monkey to obtain further insight into the link between FMPR expression and the behavioural impact of its loss in FXS. We report here the first 3D whole-brain map of FMRP expression in the Old-World monkey and show that certain brain structures display high FMRP levels, such as the cerebellum, striatum, and temporal lobe structures. This finding provides support for the notion that FMRP expression loss is linked to behavioural and cognitive impairment associated with these structures. We argue that whole-brain FMRP expression mapping may be used to formulate and test new hypotheses about other forms of impairments in FXS that were not specifically examined in this study.

Theory of mind "beliefs", developmental characteristics and social understanding in children and adolescents with intellectual disabilities

Patterns of development of ToM belief abilities in intellectually disabled (ID) children and typically developing (TD) children matched on their developmental age were investigated. The links between cognition, language, social understanding and ToM belief abilities were examined. EDEI-R [Perron-Borelli M. (1996). Echelles Différentielles d'Efficiences Intellectuelles. Forme Révisée (EDEI-R). Paris: Editions et Applications Psychologiques.] was used to match participants and to assess social understanding. ECOSSE [Lecocq P. (1996). L'E.CO.S.SE. Une épreuve de compréhension syntaxico-sémantique. Paris: Presses Universitaires du Septentrion.] assessed the level of syntactic and semantic comprehension of French speaking, to ensure a good comprehension of the questions in false belief tasks. Five tasks assessed the ability in visual perspective taking and in understanding of false belief. A difference in the global ToM ability was found between both groups (difference hypothesis in ID participants). Specific abilities in different ToM tasks showed developmental patterns partially different and partially similar, between ID and TD groups. The interest to assess the understanding of belief by means of several tasks is confirmed. Positive links between cognition, language and ToM abilities were found in both groups, but the impact of cognition and language on abilities in each ToM task is different in both groups. Finally, the specific impact of social understanding and of chronological age on abilities in false belief in ID group is discussed.

The fragile X continuum: new advances and perspectives

Fragile X syndrome is the world's most common hereditary cause of intellectual disability in men and to a lesser extent in women. The disorder is caused by the silencing of a single gene on the X chromosome, the Fragile X Mental Retardation Gene-1. A substantial body of research across the disciplines of molecular genetics, child psychiatry and developmental neuroscience bears testament to a decade of exciting and innovative science that has advanced our knowledge about the fragile X 'signature' or influence across cognitive and social development. The core aims of this review are to first discuss fragile X syndrome and premutation involvement in the context of current advances that demonstrate the dynamic nature of the genotype on phenotypic outcomes. Second, to discuss the implications of these recent advances for the development of clinical and educational interventions and resource tools that target specific phenotypic 'signatures' within the fragile X continuum.

Understanding of facial expressions of emotion by children with intellectual disabilities of differing aetiology

BACKGROUND

Interpreting emotional expressions is a socio-cognitive skill central to interpersonal interaction. Poor emotion recognition has been reported in autism but is less well understood in other kinds of intellectual disabilities (ID), with procedural differences making comparisons across studies and syndromes difficult. This study aimed to compare directly facial emotion recognition skills in children with fragile X syndrome (FXS), Down's syndrome (DS) and non-specific intellectual disability (NSID), contrasting ability and error profiles with those of typically developing (TD) children of equivalent cognitive and linguistic status.

METHODS

Sixty children participated in the study: 15 FXS, 15 DS, 15 NSID and 15 TD children. Standardised measures of cognitive, language and socialisation skills were collected for all children, along with measures of performance on two photo-matching tasks: an 'identity-matching' task (to control for basic face-processing ability) and an 'emotion-matching' task (happiness, sadness, anger, surprise, fear or disgust).

RESULTS

Identity-matching ability did not differ across the four child groups. Only the DS group performed significantly more poorly on the emotion-matching task and only in comparison to the TD group, with fear recognition an area of particular difficulty.

CONCLUSION

Findings support previous evidence of emotion recognition abilities commensurate with overall developmental level in children with FXS or NSID, but not DS. They also suggest, however, that syndrome-specific difficulties may be subtle and detectable, at least in smaller-scale studies, only in comparison with TD matches, and not always across syndromes. Implications for behavioural phenotype theory, educational interventions and future research are discussed.

Language development and fragile X syndrome: profiles, syndrome-specificity, and within-syndrome differences

Fragile X syndrome (FXS) is the leading inherited cause of mental retardation. In this article, we review what is known about the language and related problems of individuals with FXS. In doing so, we focus on the syndrome-specific features of the language phenotype and on the organismic (i.e., genetic and individual neurocognitive and behavioral) and environmental factors associated with within-syndrome variation in the phenotype. We also briefly review those aspects of the behavioral phenotype of FXS that are relevant for understanding syndrome-specific features of, and within-syndrome variability in, language. The review includes summaries of research on the prelinguistic foundations for language development and on each of the major components of language (i.e., vocabulary, morphosyntax, and pragmatics). Throughout the review, we point out implications of existing research for intervention as well as directions for future research.

Is Theory of Mind Understanding Impaired in Males with Fragile X Syndrome?

Males with fragile X syndrome (FXS) have difficulties with social interaction and many show autistic features. This study examined whether the social deficits characteristic of FXS are associated with theory of mind difficulties. Two groups of boys with FXS participated: a group with few autistic features and a group with many autistic features. An intellectual disability control group also participated. In addition to using standard theory of mind tasks, new techniques were used that were able to separate out the various processing demands of the task (e.g., memory, inhibitory control). Overall, the findings indicate that both groups of boys with FXS have difficulty with theory of mind tasks compared to an intellectual disability control group. However, both groups with FXS also performed worse on comparison trials that required working memory but not theory of mind. Theory of mind difficulties are likely to be an important aspect of the FXS clinical profile, but are most likely the result from a more basic difficulty with working memory.

Cognitive, language and social-cognitive skills of individuals with fragile X syndrome with and without autism

BACKGROUND

It is not known whether those with co-morbid fragile X syndrome (FXS) and autism represent a distinct subtype of FXS; whether the especially severe cognitive delays seen in studies of young children with co-morbid FXS and autism compared with those with only FXS continue into adolescence and young adulthood; and whether autism in those with FXS is 'true autism', i.e. reflects the same underlying problems as idiopathic autism.

METHOD

We compared the non-verbal IQ of adolescents and young adults with co-morbid FXS and autism (n = 10) with those with only FXS (n = 44). We then created a subsample of those with FXS only, matched on non-verbal IQ, mental age and gender (n = 21) to the subsample of those with co-morbid FXS and autism. We compared the two groups on measures of expressive language, receptive language (lexical, grammatical morphology and syntactic patterns), and a theory of mind task.

RESULTS

Those with co-morbid FXS and autism had lower non-verbal IQs than those with only FXS. The participants with co-morbid FXS and autism did not perform as well as the cognitive ability- and gender-matched participants with only FXS on the three measures of receptive language or the theory of mind task; there were no differences on the expressive language measure.

CONCLUSIONS

Our findings support the notion that those with co-morbid FXS and autism represent a distinct subtype of FXS, with more impairment in receptive language and theory of mind even when controlling for their lower non-verbal IQ relative to those with only FXS. The greater cognitive impairments observed in those with co-morbid FXS and autism continues into adolescence and young adulthood; and the autism seen in those with FXS appears to be the same as idiopathic autism.

Theory of mind deficits in children with fragile X syndrome

BACKGROUND

Given the consistent findings of theory of mind deficits in children with autism, it would be extremely beneficial to examine the profile of theory of mind abilities in other clinical groups such as fragile X syndrome (FXS) and Down syndrome (DS). Aim The aim of the present study was to assess whether boys with FXS are impaired in simple social situations that require them to understand their own and others' mental states - in essence: do they have a 'theory of mind'?

METHOD

Well-standardized tasks of theory of mind, the location change false belief task and the appearance-reality tasks were employed to examine whether any impairment might be specific to the FXS or part of a more generalized developmental deficit.

RESULTS

The results suggest that children with FXS do have impairment in theory of mind that is comparable to the deficit reported in other groups with learning disabilities such as DS. However, closer inspection of the impairment between these groups revealed qualitative differences in error types (realist vs. phenomenist), suggestive of atypical development that goes beyond general cognitive delay.

CONCLUSION

The findings are discussed in terms of the teasing apart of different components of social cognition in order to identify syndrome-specific deficiencies and proficiencies.

The emerging fragile X premutation phenotype: Evidence from the domain of social cognition

Fragile X syndrome is a neurodevelopmental disorder that is caused by large methylated expansions of a CGG repeat (>200) region upstream of the FMR1 gene that results in the lack of expression of the fragile X mental retardation protein (FMRP). Affected individuals display a neurobehavioral phenotype that includes a significant impairment in social cognition alongside deficits in attentional control, inhibition and working memory. In contrast, relatively little is known about the trajectory and specificity of any cognitive impairment associated with the fragile X premutation ("carrier-status") (approximately 55-200 repeats). Here, we focus on one aspect of cognition that has been well documented in the fragile X full mutation, namely social cognition. The results suggest that premutation males display a pattern of deficit similar in profile, albeit milder in presentation, to that of the full mutation. However, little evidence emerged for a correlation between CGG repeat length and severity of phenotypic outcomes. The findings are discussed in the context of functional neuroimaging and brain-behaviour-molecular correlates. We speculate that the deficiencies in social cognition are attributable to impairment of neural pathways modulated by the cerebellum.

Annotation: Deconstructing the attention deficit in fragile X syndrome: a developmental neuropsychological approach

BACKGROUND

Fragile X syndrome is one of the world's leading hereditary causes of developmental delay in males. The past decade has witnessed an explosion of research that has begun to unravel the condition at its various levels: from the genetic and brain levels to the cognitive level, and then to the environmental and behavioural levels. Our aim in this review is to attempt to integrate some of the extensive body of knowledge to move the research a step closer to understanding how the dynamics of atypical development can influence the specific cognitive and behavioural end-states frequently observed in children and adolescents with fragile X syndrome.

METHODS

We conducted a review of the current neuropsychological and neuropsychiatric approaches that have attempted to delineate the pattern of 'spared' and 'impaired' functions associated with the phenotype.

RESULTS

The profile of findings suggests that fragile X syndrome should not be viewed merely as a catalogue of spared and impaired cognitive functions or modules. Instead, there appears to be a process of almost gradual modularisation whereby cognitive mechanisms become domain specific as a function of development itself (Karmiloff-Smith, 1992). The results of a decade of intense research point towards an early weakness in one or more components of executive control rather than single, static higher-level deficits (e.g., spatial cognition, speech processing). This weakness affects both the development of more complex functions and current performance.

CONCLUSIONS

The prevailing tendency to interpret developmental disorders in terms of fixed damage to distinct modular functions needs to be reconsidered. We offer this review as an example of an alternative approach, attempting to identify an initial deficit and its consequences for the course of development. Through better definition of the cognitive and behavioural phenotype, in combination with current progress in brain imaging techniques and molecular studies, the next decade should continue to hold exciting promise for fragile X syndrome and other neurodevelopmental disorders.

Relationship between theory of mind and language ability in children and adolescents with intellectual disability

BACKGROUND

The present study was designed to evaluate the validity of the false belief task as a measure of theory of mind development in individuals with intellectual disability (ID). In most if it variants, the false belief task is linguistically demanding. This raises the possibility that the finding that individuals with ID do poorly on it might reflect language difficulties rather than theory of mind difficulties. Complicating matters further, however, is the fact that there are theoretical reasons to suppose that there might be a relationship between some dimensions of language ability and theory of mind development in individuals with ID (as well as in other populations).

METHOD

In the present study, children and adolescents with ID and typically developing (non-verbal) mental age matches completed a standard false belief task and several tasks designed to measure language ability.

RESULTS

We reasoned that a pattern in which false belief performance was correlated with all measures of language ability would reflect an artefactual relationship, whereas a more highly circumscribed, theoretically sensible pattern of correlations that was similar across both groups would support the validity of the false belief task.

CONCLUSIONS

The results indicated that for individuals with ID who have limited narrative language skills, those limitations contribute substantially to their failure on the false belief task. For individuals with ID who have more highly developed narrative language skills (about 40% of the sample tested), however, the false belief task may provide a valid measure of their progress towards acquiring an adequate theory of mind. This latter conclusion was suggested by the fact screening out individuals who failed to meet linguistic and cognitive prerequisites for dealing with the performance demands of the false belief task yielded non-significant correlations between false belief performance and the language measures for both the group with ID and the typically developing comparison group.