Early development, temperament, and functional impairment in autism and fragile X syndrome

Autism Spectrum Disorder Symptom Profiles in Fragile X Syndrome, Angelman Syndrome, Tuberous Sclerosis Complex and Neurofibromatosis Type 1

Studying Autism Spectrum Disorder (ASD) heterogeneity in biologically homogeneous samples may increase our knowledge of ASD etiology. Fragile X syndrome (FXS), Angelman syndrome (AS), Tuberous Sclerosis Complex (TSC), and Neurofibromatosis type 1 (NF1) are monogenic disorders with high a prevalence of ASD symptomatology. This study aimed to identify ASD symptom profiles in a large group of children and adolescents (0;9-28 years) with FXS, AS, TSC, and NF1. Data on ASD symptomatology (Autism Diagnostic Observation Scale (ADOS-2) & Social Responsiveness Scale (SRS-2)) were collected from children and adolescents with FXS (n = 54), AS (n = 93), TSC (n = 112), and NF1 (n = 278). To identify groups of individuals with similar ASD profiles, we performed two latent profile analyses. We identified a four-profile model based on the ADOS-2, with a (1) 'Non-spectrum symptom profile', (2) 'Social Affect symptom profile', (3)'Restricted/Repetitive Behaviors symptom profile', and (4)'ASD symptom profile'. We also identified a four-profile model based on the SRS, with a (1)'Non-clinical symptom profile', (2)'Mild symptom profile', (3)'Moderate symptom profile', and (4)'Severe symptom profile'. Although each syndrome group exhibited varying degrees of severity, they also displayed heterogeneity in the profiles in which they were classified. We found distinct ASD symptom profiles in a population consisting of children and adolescents with FXS, AS, TSC, and NF1. Our study highlights the importance of a personalized approach to the identification and management of ASD symptoms in rare genetic syndromes. Future studies should aim to include more domains of functioning and investigate the stability of latent profiles over time.

Cholesterol alterations in fragile X syndrome, autism spectrum disorders and other neurodevelopmental disorders

Neurodevelopmental disorders (NDDs) are a group of etiologically diverse diseases primarily associated with abnormal brain development, impaired cognition, and various behavioral problems. The majority of NDDs present a wide range of clinical phenotypes while sharing distinct cellular and biochemical alterations. Low plasma cholesterol levels have been reported in a subset of NNDs including, autism spectrum disorder (ASD) and fragile X syndrome (FXS). The present review focuses on cholesterol metabolism and discusses the current evidence of lipid disruption in ASD, FXS, and other genetically related NDDs. The characterization of these common deficits might provide valuable insights into their underlying physiopathology and help identify potential therapeutic targets.

Working Memory Training in Youth With Autism, Fragile X, and Intellectual Disability: A Pilot Study

This pilot study sought to identify potential markers of improvement from pre-post treatment in response to computerized working memory (WM) training for youth (ages 8-18) with autism spectrum disorder (ASD) and comorbid intellectual disability (ID) in a single arm, pre-post design. Participants included 26 children with ASD and 18 with comorbid ASD and fragile X syndrome (ASD+FXS). Analyses were adjusted for age and IQ. The ASD group demonstrated greater improvement on WM training relative to the ASD+FXS group. Participants improved on WM and far transfer outcomes, however, there were no significant group differences in improvement except for repetitive behavior. Higher hyperactivity/impulsivity ratings predicted lower performance on visuospatial WM. Findings suggest cognitive training may be beneficial for youth with ASD and ID, warranting further exploration.

Infant Effortful Control Mediates Relations Between Nondirective Parenting and Internalising-Related Child Behaviours in an Autism-Enriched Infant Cohort

Internalising problems are common within Autism Spectrum Disorder (ASD); early intervention to support those with emerging signs may be warranted. One promising signal lies in how individual differences in temperament are shaped by parenting. Our longitudinal study of infants with and without an older sibling with ASD investigated how parenting associates with infant behavioural inhibition (8-14 months) and later effortful control (24 months) in relation to 3-year internalising symptoms. Mediation analyses suggest nondirective parenting (8 months) was related to fewer internalising problems through an increase in effortful control. Parenting did not moderate the stable predictive relation of behavioural inhibition on later internalising. We discuss the potential for parenting to strengthen protective factors against internalising in infants from an ASD-enriched cohort.

Behavior Problems and Social Competence in Fragile X Syndrome: A Systematic Review

Fragile X syndrome (FXS) causes intellectual disability and is the known leading cause of autism. Common problems in FXS include behavior and social problems. Along with syndromic characteristics and autism comorbidity, environmental factors might influence these difficulties. This systematic review focuses on the last 20 years of studies concerning behavior and social problems in FXS, considering environmental and personal variables that might influence both problems. Three databases were reviewed, leading to fifty-one studies meeting the inclusion criteria. Attention deficit hyperactivity disorder (ADHD) problems remain the greatest behavior problems, with behavioral problems and social competence being stable during the 20 years. Some developmental trajectories might have changed due to higher methodological control, such as aggressive behavior and attention problems. The socialization trajectory from childhood to adolescence remains unclear. Comorbidity with autism in individuals with FXS increased behavior problems and worsened social competence profiles. At the same time, comparisons between individuals with comorbid FXS and autism and individuals with autism might help define the comorbid phenotype. Environmental factors and parental characteristics influenced behavior problems and social competence. Higher methodological control is needed in studies including autism symptomatology and parental characteristics. More studies comparing autism in FXS with idiopathic autism are needed to discern differences between conditions.

Autism Symptoms in Children and Young Adults With Fragile X Syndrome, Angelman Syndrome, Tuberous Sclerosis Complex, and Neurofibromatosis Type 1: A Cross-Syndrome Comparison

OBJECTIVE

The etiology of autism spectrum disorder (ASD) remains unclear, due to genetic heterogeneity and heterogeneity in symptoms across individuals. This study compares ASD symptomatology between monogenetic syndromes with a high ASD prevalence, in order to reveal syndrome specific vulnerabilities and to clarify how genetic variations affect ASD symptom presentation.

METHODS

We assessed ASD symptom severity in children and young adults (aged 0-28 years) with Fragile X Syndrome (FXS, n = 60), Angelman Syndrome (AS, n = 91), Neurofibromatosis Type 1 (NF1, n = 279) and Tuberous Sclerosis Complex (TSC, n = 110), using the Autism Diagnostic Observation Schedule and Social Responsiveness Scale. Assessments were part of routine clinical care at the ENCORE expertise center in Rotterdam, the Netherlands. First, we compared the syndrome groups on the ASD classification prevalence and ASD severity scores. Then, we compared individuals in our syndrome groups with an ASD classification to a non-syndromic ASD group (nsASD, n = 335), on both ASD severity scores and ASD symptom profiles. Severity scores were compared using MANCOVAs with IQ and gender as covariates.

RESULTS

Overall, ASD severity scores were highest for the FXS group and lowest for the NF1 group. Compared to nsASD, individuals with an ASD classification in our syndrome groups showed less problems on the instruments' social domains. We found a relative strength in the AS group on the social cognition, communication and motivation domains and a relative challenge in creativity; a relative strength of the NF1 group on the restricted interests and repetitive behavior scale; and a relative challenge in the FXS and TSC groups on the restricted interests and repetitive behavior domain.

CONCLUSION

The syndrome-specific strengths and challenges we found provide a frame of reference to evaluate an individual's symptoms relative to the larger syndromic population and to guide treatment decisions. Our findings support the need for personalized care and a dimensional, symptom-based diagnostic approach, in contrast to a dichotomous ASD diagnosis used as a prerequisite for access to healthcare services. Similarities in ASD symptom profiles between AS and FXS, and between NF1 and TSC may reflect similarities in their neurobiology. Deep phenotyping studies are required to link neurobiological markers to ASD symptomatology.

Parental Reports on Early Autism Behaviors in Their Children with Fragile X Syndrome as a Function of Infant Feeding

This study evaluates the prevalence of autistic behaviors in fragile X syndrome as a function of infant diet. Retrospective survey data from the Fragile X Syndrome Nutrition Study, which included data on infant feeding and caregiver-reported developmental milestones for 190 children with fragile X syndrome enrolled in the Fragile X Online Registry with Accessible Database (FORWARD), were analyzed. Exploratory, sex-specific associations were found linking the use of soy-based infant formula with worse autistic behaviors related to language in females and self-injurious behavior in males. These findings prompt prospective evaluation of the effects of soy-based infant formula on disease comorbidities in fragile X syndrome, a rare disorder for which newborn screening could be implemented if there was an intervention. Gastrointestinal problems were the most common reason cited for switching to soy-based infant formula. Thus, these findings also support the study of early gastrointestinal problems in fragile X syndrome, which may underly the development and severity of disease comorbidities. In conjunction with comorbidity data from the previous analyses of the Fragile X Syndrome Nutrition Study, the findings indicate that premutation fragile X mothers should be encouraged to breastfeed.

Developmental Paths to Anxiety in an Autism-Enriched Infant Cohort: The Role of Temperamental Reactivity and Regulation

The aim of this study was to explore the associations between temperamental reactivity and regulation and the emergence of anxiety traits in a longitudinal sample of infants enriched for later ASD. Parents of 143 infants who were at high- and low-risk for ASD rated their child’s temperament traits when they were 9, 15 and 24 months old; they rated anxiety and ASD traits when they were 36 months old. The findings suggest that behavioural inhibition may be an early predictor of later anxiety in children with and without ASD and that lower levels of effortful control in children who later develop ASD may contribute to the higher expression of anxiety within this population.

Emergence of Developmental Delay in Infants and Toddlers With an FMR1 Mutation

BACKGROUND

Children with FMR1 gene expansions are known to experience a range of developmental challenges, including fragile X syndrome. However, little is known about early development and symptom onset, information that is critical to guide earlier identification, more accurate prognoses, and improved treatment options.

METHODS

Data from 8 unique studies that used the Mullen Scales of Early Learning to assess children with an FMR1 gene expansion were combined to create a data set of 1178 observations of >500 young children. Linear mixed modeling was used to explore developmental trajectories, symptom onset, and unique developmental profiles of children <5 years of age.

RESULTS

Boys with an FMR1 gene full mutation showed delays in early learning, motor skills, and language development as young as 6 months of age, and both sexes with a full mutation were delayed on all developmental domains by their second birthday. Boys with a full mutation continued to gain skills over early childhood at around half the rate of their typically developing peers; girls with a full mutation showed growth at around three-quarters of the rate of their typically developing peers. Although children with a premutation were mostly typical in their developmental profiles and trajectories, mild but significant delays in fine motor skills by 18 months were detected.

CONCLUSIONS

Children with the FMR1 gene full mutation demonstrate significant developmental challenges within the first 2 years of life, suggesting that earlier identification is needed to facilitate earlier implementation of interventions and therapeutics to maximize effectiveness.

Associations Between Emotional Competence and Prosocial Behaviors With Peers Among Children With Autism Spectrum Disorder

Children with autism spectrum disorder (ASD) are at risk for disrupted peer interactions. This study contributes to our understanding of how multiple foundational elements of emotional competence are related to children's prosocial behaviors with peers. Children with ASD demonstrated significantly lower non-stereotypical affective perspective taking, had lower ratings of emotion regulation, and showed differences from their typical peers in the use of discrete coping strategies during peer interactions. Children's emotion regulation and use of discrete coping strategies in the context of peers were associated with their prosocial behaviors one year later. The findings add to our understanding of how emotional development contributes to individual differences in the social-emotional behaviors of children with ASD. Implications for intervention are discussed.

Temperament in individuals with Autism Spectrum Disorder: A systematic review

The study of temperament in Autism Spectrum Disorder (ASD) has the potential to provide insight regarding variability in the onset, nature, and course of both core and co-morbid symptoms. The aim of this systematic review was to integrate existing findings concerning temperament in the context of ASD. Searches of Medline, PsychInfo and Scopus databases identified 64 relevant studies. As a group, children and adolescents with ASD appear to be temperamentally different from both typically developing and other clinical non-ASD groups, characterized by higher negative affectivity, lower surgency, and lower effortful control at a higher-order level. Consistent with research on typically developing children, correlational findings and emerging longitudinal evidence suggests that lower effortful control and higher negative affect are associated with increased internalizing and externalizing problems in ASD samples. Longitudinal studies suggest there may be temperamental differences between high familial risk infants who do and do not develop ASD from as early as 6-months of age. Limitations of existing research are highlighted, and possible directions for future research to capitalize on the potential afforded through the study of temperament in relation to ASD are discussed.

Spontaneous motor-behavior abnormalities in two Drosophila models of neurodevelopmental disorders

Mutations in hundreds of genes cause neurodevelopmental disorders with abnormal motor behavior alongside cognitive deficits. Boys with fragile X syndrome (FXS), a leading monogenic cause of intellectual disability, often display repetitive behaviors, a core feature of autism. By direct observation and manual analysis, we characterized spontaneous-motor-behavior phenotypes of Drosophila dfmr1 mutants, an established model for FXS. We recorded individual 1-day-old adult flies, with mature nervous systems and prior to the onset of aging, in small arenas. We scored behavior using open-source video-annotation software to generate continuous activity timelines, which were represented graphically and quantitatively. Young dfmr1 mutants spent excessive time grooming, with increased bout number and duration; both were rescued by transgenic wild-type dfmr1⁺. By two grooming-pattern measures, dfmr1-mutant flies showed elevated repetitions consistent with perseveration, which is common in FXS. In addition, the mutant flies display a preference for grooming posterior body structures, and an increased rate of grooming transitions from one site to another. We raise the possibility that courtship and circadian rhythm defects, previously reported for dfmr1 mutants, are complicated by excessive grooming. We also observed significantly increased grooming in CASK mutants, despite their dramatically decreased walking phenotype. The mutant flies, a model for human CASK-related neurodevelopmental disorders, displayed consistently elevated grooming indices throughout the assay, but transient locomotory activation immediately after placement in the arena. Based on published data identifying FMRP-target transcripts and functional analyses of mutations causing human genetic neurodevelopmental disorders, we propose the following proteins as candidate mediators of excessive repetitive behaviors in FXS: CaMKIIα, NMDA receptor subunits 2A and 2B, NLGN3, and SHANK3. Together, these fly-mutant phenotypes and mechanistic insights provide starting points for drug discovery to identify compounds that reduce dysfunctional repetitive behaviors.

Wnd/DLK Is a Critical Target of FMRP Responsible for Neurodevelopmental and Behavior Defects in the Drosophila Model of Fragile X Syndrome

Fragile X syndrome (FXS) is the leading heritable cause of intellectual disability and commonly co-occurs with autism spectrum disorder. Silencing of the Fmr1 gene leads to the absence of the protein product, fragile X mental retardation protein (FMRP), which represses translation of many target mRNAs. Excess translation of these targets is one cause of neuronal dysfunction in FXS. Utilizing the Drosophila model of FXS, we identified the mitogen-activated protein kinase kinase kinase (MAP3K) Wallenda/dual leucine zipper kinase (DLK) as a critical target of FMRP. dFMRP binds Wallenda mRNA and is required to limit Wallenda protein levels. In dFmr1 mutants, Wallenda signaling drives defects in synaptic development, neuronal morphology, and behavior. Pharmacological inhibition of Wallenda in larvae suppresses dFmr1 neurodevelopmental phenotypes, while adult administration prevents dFmr1 behavioral defects. We propose that in dFmr1 mutants chronic Wallenda/DLK signaling disrupts nervous system development and function and that inhibition of this kinase cascade might be a candidate therapeutic intervention for the treatment of FXS.

Russo and DiAntonio identify a dysregulated MAPK signaling pathway in the fly model of fragile X syndrome. MAP3K Wnd/DLK drives dFmr1 mutant phenotypes, and pharmacological inhibition of Wnd/DLK prevents neural dysfunction in this model, thus highlighting a possible role for Wnd/DLK in the pathophysiology of fragile X syndrome.

The temperament features associated with autism spectrum disorder in childhood: A systematic review

BACKGROUND

Temperament is an important construct that shapes child development. Temperament is suggested to present differently in different groups, such as children with neurodevelopmental disorders. However, it is not known whether there are specific temperament features associated with Autism Spectrum Disorder (ASD).

AIM

This systematic review aimed to synthesise extant literature to determine whether there are temperament features associated with ASD in infancy, toddlerhood and childhood.

METHODS AND PROCEDURES

Following the PRISMA guidelines for systematic reviews, we searched PsycINFO, CINAHL, Academic Search Ultimate and ProQuest for all available articles from database conception until January 2020. The Joanna Briggs Institute Critical Appraisal checklists were used to assess the methodological quality of included articles.

OUTCOMES AND RESULTS

Twenty-six articles met the selection criteria: (1) reported on the temperament of children (0-12 years of age) diagnosed with ASD, (2) peer-reviewed; and (3) published in English. Articles varied in overall methodological quality. Infants later diagnosed with ASD were found to more frequently be described as having 'easy' temperament features in early infancy, compared to typically developing infants and infants with developmental concerns but not ASD. Once diagnosed, children with ASD were reported to, as a group, display more negative affect, less extraversion and less effortful control than typically developing children.

CONCLUSIONS AND IMPLICATIONS

The literature suggests that more challenging temperament features are associated with ASD in childhood, but less is known about within group variability. Overall, this review highlights the need for further investigation into the variability of temperament in children with ASD.

The RNA-binding fragile-X mental retardation protein and its role beyond the brain

It is well-established that variations of a CGG repeat expansion in the gene FMR1, which encodes the fragile-X mental retardation protein (FMRP), cause the neurocognitive disorder, fragile-X syndrome (FXS). However, multiple observations suggest a general and complex regulatory role of FMRP in processes outside the brain: (1) FMRP is ubiquitously expressed in the body, suggesting it functions in multiple organ systems; (2) patients with FXS can exhibit a physical phenotype that is consistent with an underlying abnormality in connective tissue; (3) different CGG repeat expansion lengths in FMR1 result in different clinical outcomes due to different pathogenic mechanisms; (4) the function of FMRP as an RNA-binding protein suggests it has a general regulatory role. This review details the complex nature of FMRP and the different CGG repeat expansion lengths and the evidence supporting the essential role of the protein in a variety of biological and pathological processes.

Developmental studies in fragile X syndrome

Fragile X syndrome (FXS) is the most common single gene cause of autism and intellectual disabilities. Humans with FXS exhibit increased anxiety, sensory hypersensitivity, seizures, repetitive behaviors, cognitive inflexibility, and social behavioral impairments. The main purpose of this review is to summarize developmental studies of FXS in humans and in the mouse model, the Fmr1 knockout mouse. The literature presents considerable evidence that a number of early developmental deficits can be identified and that these early deficits chart a course of altered developmental experience leading to symptoms well characterized in adolescents and adults. Nevertheless, a number of critical issues remain unclear or untested regarding the development of symptomology and underlying mechanisms. First, what is the role of FMRP, the protein product of Fmr1 gene, during different developmental ages? Does the absence of FMRP during early development lead to irreversible changes, or could reintroduction of FMRP or therapeutics aimed at FMRP-interacting proteins/pathways hold promise when provided in adults? These questions have implications for clinical trial designs in terms of optimal treatment windows, but few studies have systematically addressed these issues in preclinical and clinical work. Published studies also point to complex trajectories of symptom development, leading to the conclusion that single developmental time point studies are unlikely to disambiguate effects of genetic mutation from effects of altered developmental experience and compensatory plasticity. We conclude by suggesting a number of experiments needed to address these major gaps in the field.

Changes in temperament over time in young children with autism spectrum disorder and other developmental delays: a follow-up comparison study

BACKGROUND

Although in the last decade some research has emerged on temperament in autism spectrum disorder (ASD), this research has primarily focused on the differences between children with ASD and their typically developing peers rather than the stability or change in temperament in this population. Thus, the goal of this study was to examine temperament over time in children with ASD, developmental delays (DD) and typical development (TD). Temperament differences were also compared among the three groups.

METHODS

To accomplish this, parents rated children's temperament at Time 1 (T1) and Time 2 (T2) using the Carey Temperament Scales (CTS).

RESULTS

Results from the study showed that at T1, parents of children with ASD rated their children as more withdrawn (i.e. approach), and emotionally negative (i.e. mood), and less distractible and adaptable than parents of children with TD and DD. Also, children with ASD were rated as more intense and children with DD as less distractible than their TD peers. Similarly, at T2, children with ASD were rated more withdrawn, and emotionally negative, and less persistent, rhythmic, adaptable and distractible than children with TD and DD. Also, children with ASD were rated as more active than their DD peers. Regarding stability, parent ratings of temperament appeared stable over time in the TD group, but ratings varied substantially in the ASD or DD groups. That is, for the ASD group, activity and approach at T1 were significantly associated with their corresponding dimensions at T2. However, for the TD group, rhythmicity, approach, intensity and mood at T1 were significantly associated with those dimensions at T2. No associations were found in the DD group. Regarding change, parents reported change in rhythmicity, persistence and threshold between T1 and T2 in the ASD group. Similarly, parents reported change in rhythmicity, approach and threshold between T1 and T2 in the DD group. Lastly, parents of TD children reported change in adaptability, persistence and distractibility between T1 and T2.

CONCLUSIONS

These findings are novel in that children with ASD appear to have less stable temperament profile and different change patterns than children with TD or DD. Similar to previous research, children with ASD were described by their parents as experiencing more temperamental difficulties.

Temperament Similarities and Differences: A Comparison of Factor Structures from the Behavioral Style Questionnaire in Children with and Without Autism Spectrum Disorder

The majority of studies of temperament in children with autism spectrum disorder (ASD) use scales normed on typical populations. The present study examined a widely used measure of temperament, the Behavioral Style Questionnaire (McDevitt and Carey in Behavioral Styles Questionnaire, Behavioral-Developmental Initiatives Scottsdale, AZ, 1975) to determine whether it contains the temperament traits theorized by its creators. Neither confirmatory nor exploratory factor analysis, using a sample of children with ASD and a population comparison group, identified the theorized nine temperament factors; many items did not strongly load on any of the original factors. A 10 factor solution best described the ASD data and a 9 factor solution best described the typical group's data. There were substantial similarities in the 9 factor solutions, but groups differed from one another enough to question construct similarity for several factors. These results highlight that more basic psychometric research is needed to better understand the BSQ in children with ASD.

CYFIP1 overexpression increases fear response in mice but does not affect social or repetitive behavioral phenotypes

Background

CYFIP1, a protein that interacts with FMRP and regulates protein synthesis and actin dynamics, is overexpressed in Dup15q syndrome as well as autism spectrum disorder (ASD). While CYFIP1 heterozygosity has been rigorously studied due to its loss in 15q11.2 deletion, Prader-Willi and Angelman syndrome, the effects of CYFIP1 overexpression, as is observed in patients with CYFIP1 duplication, are less well understood.

Methods

We developed and validated a mouse model of human CYFIP1 overexpression (CYFIP1 OE) using qPCR and western blot analysis. We performed a large battery of behavior testing on these mice, including ultrasonic vocalizations, three-chamber social assay, home-cage behavior, Y-maze, elevated plus maze, open field test, Morris water maze, fear conditioning, prepulse inhibition, and the hot plate assay. We also performed RNA sequencing and analysis on the basolateral amygdala.

Results

Extensive behavioral testing in CYFIP1 OE mice reveals no changes in the core behaviors related to ASD: social interactions and repetitive behaviors. However, we did observe mild learning deficits and an exaggerated fear response. Using RNA sequencing of the basolateral amygdala, a region associated with fear response, we observed changes in pathways related to cytoskeletal regulation, oligodendrocytes, and myelination. We also identified GABA-A subunit composition changes in basolateral amygdala neurons, which are essential components of the neural fear conditioning circuit.

Conclusion

Overall, this research identifies the behavioral and molecular consequences of CYFIP1 overexpression and how they contribute to the variable phenotype seen in Dup15q syndrome and in ASD patients with excess CYFIP1.

ASD Comorbidity in Fragile X Syndrome: Symptom Profile and Predictors of Symptom Severity in Adolescent and Young Adult Males

Many males with FXS meet criteria for ASD. This study was designed to (1) describe ASD symptoms in adolescent and young adult males with FXS (n = 44) and (2) evaluate the contributions to ASD severity of cognitive, language, and psychiatric factors, as well as FMRP (the protein deficient in FXS). A few ASD symptoms on the ADOS-2 were universal in the sample. There was less impairment in restricted and repetitive behaviors (RRB) than in the social affective (SA) domain. The best predictor of overall ASD severity and SA severity was expressive syntactic ability. RRB severity was best predicted by the psychiatric factors. Implications for clinical practice and for understanding the ASD comorbidity in FXS are discussed.

Prevalence and Predictors of Anxiety Disorders in Adolescent and Adult Males with Autism Spectrum Disorder and Fragile X Syndrome

Anxiety disorders affect ~ 15-20% of youths without neurodevelopmental disorders, with persons having autism spectrum disorder (ASD) and fragile X syndrome (FXS) at elevated risk for anxiety disorders. Few studies have compared rates and predictors of anxiety disorders in adolescents with FXS or ASD. This study directly compares rates, predictors, and medication of anxiety disorders between age-matched, male adolescents with FXS (n = 31) or ASD (n = 20). Results indicate that 51.6% of FXS and 50.0% of ASD adolescents met criteria for an anxiety disorder. Cognitive scores and ASD severity did not predict anxiety. Of those with anxiety, ~ 40% of the FXS and 20% of the ASD participants were prescribed medications for anxiety.

Differentiating social preference and social anxiety phenotypes in fragile X syndrome using an eye gaze analysis: a pilot study

Background

Fragile X syndrome (FXS) is the leading inherited cause of autism spectrum disorder, but there remains debate regarding the clinical presentation of social deficits in FXS. The aim of this study was to compare individuals with FXS to typically developing controls (TDC) and individuals with idiopathic autism spectrum disorder (ASD) across two social eye tracking paradigms.

Methods

Individuals with FXS and age- and gender-matched TDC and individuals with idiopathic ASD completed emotional face and social preference eye tracking tasks to evaluate gaze aversion and social interest, respectively. Participants completed a battery of cognitive testing and caregiver-reported measures for neurobehavioral characterization.

Results

Individuals with FXS exhibited reduced eye and increased mouth gaze to emotional faces compared to TDC. Gaze aversive findings were found to correlate with measures of anxiety, social communication deficits, and behavioral problems. In the social interest task, while individuals with idiopathic ASD showed significantly less social preference, individuals with FXS displayed social preference similar to TDC.

Conclusions

These findings suggest fragile X syndrome social deficits center on social anxiety without the prominent reduction in social interest associated with autism spectrum disorder. Specifically designed eye tracking techniques clarify the nature of social deficits in fragile X syndrome and may have applications to improve phenotyping and evaluate interventions targeting social functioning impairments.

Infant Temperament in the FMR1 Premutation and Fragile X Syndrome

Although temperament has been studied for decades as a predictor of psychopathology in the general population, examining temperament in neurogenetic groups has unique potential to inform the genetic and biological factors that may confer risk for psychopathology in later development. The present study examined early temperament in two heritable neurogenetic conditions associated with atypical CGG repeat expansions on the FMR1 gene: the FMR1 premutation (FXpm; 55-200 repeats) and fragile X syndrome (FXS; > 200 repeats). We focus specifically on the FXpm, as the condition is highly prevalent (1:209-291 female individuals, 1:430-855 male individuals) and has been preliminarily associated with increased risk for pediatric psychopathology, including attention problems, autism, and anxiety. In contrast, FXS is a low-incidence disorder (1:7,143 males, 1:11,111 females) often associated with intellectual disability and severe co-occurring psychosocial conditions, particularly in male individuals. Given information on infant clinical phenotypes in the FXpm and FXS is sparse, we aimed to characterize parent-reported infant temperament in infants with the FXpm (n = 22) relative to FXS (n = 24) and controls (n = 24) assessed on 1 to 3 occasions each. Temperament in infants with the FXpm largely fell between TD and FXS groups, with trends toward suppressed negative affect in younger participants, similar to lower negative affect previously reported in FXS. The FXS group consistently demonstrated lower negative affect and surgency than TD controls. These data suggest that FMR1 gene mutations are associated with atypical temperament that emerges as early as infancy, particularly among infants with FXS, warranting further study of whether temperament may index emergent clinical risks in these populations.

Specificity: A Phenotypic Comparison of Communication-Relevant Domains Between Youth With Down Syndrome and Fragile X Syndrome

Despite the shared presence of an intellectual disability (ID), there is a growing literature documenting important phenotypic differences between Down syndrome (DS) and fragile X syndrome (FXS). These conclusions, however, are based on a synthesis across studies, each of which typically includes only measures of a limited number of constructs, and with differing participant characteristics. Firmer conclusions regarding specific phenotypes require a single comprehensive multi-domain assessment of participants with the syndrome groups being well matched on chronological age (CA) and cognitive functioning. The current study was designed to fill this gap by assessing several important cognitive and behavioral domains relevant to communication, such as: structural language skills, false belief understanding, as well as pragmatics and behavioral difficulties, in 30 adolescents of both sexes with DS and 39 males with FXS, matched on CA and nonverbal (NV) cognition. After statistically controlling for NV cognition, we did not find significant syndrome differences in expressive and receptive structural language or false belief understanding. In contrast, participants with DS displayed less stereotyped language and fewer behavioral difficulties compared to males with FXS. Within-syndrome associations among the targeted domains are described. Finally, females with DS were less impaired than males with DS in almost all structural language domains, whereas no significant sex-related differences were observed in NV cognition, false belief understanding, pragmatics, or behavior. Clinical and methodological implications of the findings are discussed.

A comparison of functional academic and daily living skills in males with fragile X syndrome with and without autism

BACKGROUND

Adaptive behaviors, such as functional academic and daily living skills, are critical for independence in adults with intellectual and developmental disabilities. However, little is known about these skills in fragile X syndrome (FXS), the most common form of inherited intellectual disability.

AIMS

The purposes of this study were to describe the functional academic and daily living skills of males diagnosed with FXS across different age groups and compare skill attainment by autism status and other common co-occurring conditions.

METHODS AND PROCEDURES

We used survey methods to assess parent-reported functional academic and daily living skills in 534 males with FXS. Functional academic skills included time and schedules, money, math, reading, and writing skills. Daily living skills included hygiene, cooking, laundry and housekeeping, transportation, and safety skills.

OUTCOMES AND RESULTS

Analyses examined functional academic and daily living skills in a cross-sectional sample of males between ages 5 and 67. Differences in skill attainment were found by child age, co-morbid autism status, total number of co-occurring conditions, and respondent education. Functional academic and daily living skills were predictive of community employment and independent living.

CONCLUSIONS AND IMPLICATIONS

These data provide important information on the mastery of both foundational and more complex adaptive skills in males with FXS. Both functional academic and daily living skills were predictive of measures of independence above and beyond other child and family characteristics. These findings point to the need to focus interventions to support the attainment of independence in males with FXS.

The Emergence of Effortful Control in Young Boys With Fragile X Syndrome

Effortful control, or the ability to suppress a dominant response to perform a subdominant response, is an early-emerging temperament trait that is linked with positive social-emotional development. Fragile X syndrome (FXS) is a single-gene disorder characterized by hallmark regulatory impairments, suggesting diminished effortful control. This study compared the development of effortful control in preschool boys with FXS ( n = 97) and typical development ( n = 32). Unlike their typical peers, the boys with FXS did not exhibit growth in effortful control over time, which could not be accounted for by adaptive impairments, FMR1 molecular measures, or autism symptoms. These results contribute to our understanding of the childhood phenotype of FXS that may be linked to the poor social-emotional outcomes seen in this group.

Differential Relationships of Anxiety and Autism Symptoms on Social Skills in Young Boys With Fragile X Syndrome

Social skills are critical for academic, social, and psychological success of children with both typical and atypical development. Boys with fragile X syndrome (FXS) are at high risk for social skill impairments, given intellectual impairments and secondary conditions. The present study examines the impact of adaptive behavior, autism symptoms, and anxiety symptoms to social skills at the composite and subdomain level in boys with FXS across age. This cross-sectional study included boys with FXS (3-14 years) contrasted to age-matched typical control boys. Results revealed that social skills are generally within developmental expectations, with adaptive behavior as the primary predictor. Anxiety and autism symptoms emerged as additive risk factors, particularly in the areas of responsibility and self-control.

Temperamental markers in toddlers with autism spectrum disorder

BACKGROUND

Although temperament has been recognized as an important contributor to childhood psychopathology, its role in emergent autism spectrum phenotypes is not well understood. This study examined whether toddlers with autism spectrum disorder (ASD) display temperamental vulnerabilities compared to toddlers with other developmental challenges, whether these characteristics are distinct from core autism symptoms, if they are stable over time, and if they contribute to social outcomes in preschool.

METHODS

Parents of 165 toddlers with ASD, 58 nonverbal ability- and chronological age- (CA) matched developmentally delayed (DD) toddlers, and 92 CA-matched typically developing (TD) toddlers completed the Toddler Behavior Assessment Questionnaire-Supplemental (TBAQ-S) at 26 months (SD = 6; Time 1). TBAQ-S data were also available for a subset of toddlers with ASD (n = 126) at 43 months (SD = 9; Time 2).

RESULTS

Compared to the DD and TD groups, toddlers with ASD exhibited vulnerabilities within the Effortful Control domain as well as the Surgency domain. They also displayed greater Negative Emotionality compared to TD peers. In the ASD group, temperamental characteristics were not concurrently related to autism severity or developmental level and individual differences were highly stable over time. Changes in Perceptual Sensitivity, Inhibitory Control, and Low-Intensity Pleasure from age 2 to 3.5 uniquely predicted autism symptom severity and adaptive social skill level at Time 2.

CONCLUSIONS

Temperamental vulnerabilities in toddlers with ASD are stable over time and involve attentional and behavioral control as well as affective reactivity. They contribute uniquely to social outcomes in preschool and are likely to signal risk for developing later maladaptive attentional, affective, and behavioral symptoms. Considering biologically based dimensions may shed light on noncore facets of the early ASD phenotype that are potentially relevant to the emergence of comorbid conditions later in childhood.

Public Health Literature Review of Fragile X Syndrome

OBJECTIVES

The purpose of this systematic literature review is to describe what is known about fragile X syndrome (FXS) and to identify research gaps. The results can be used to help inform future public health research and provide pediatricians with up-to-date information about the implications of the condition for individuals and their families.

METHODS

An electronic literature search was conducted, guided by a variety of key words. The search focused on 4 areas of both clinical and public health importance: (1) the full mutation phenotype, (2) developmental trajectories across the life span, (3) available interventions and treatments, and (4) impact on the family. A total of 661 articles were examined and 203 were included in the review.

RESULTS

The information is presented in the following categories: developmental profile (cognition, language, functional skills, and transition to adulthood), social-emotional profile (cooccurring psychiatric conditions and behavior problems), medical profile (physical features, seizures, sleep, health problems, and physiologic features), treatment and interventions (educational/behavioral, allied health services, and pharmacologic), and impact on the family (family environment and financial impact). Research gaps also are presented.

CONCLUSIONS

The identification and treatment of FXS remains an important public health and clinical concern. The information presented in this article provides a more robust understanding of FXS and the impact of this complex condition for pediatricians. Despite a wealth of information about the condition, much work remains to fully support affected individuals and their families.

The impact of autism spectrum disorder symptoms on gesture use in fragile X syndrome and Down syndrome

BACKGROUND & AIMS

This study compared gesture rate and purpose in participants with Down syndrome (DS) and fragile X syndrome (FXS), and the impact of autism spectrum disorder (ASD) symptoms on each syndrome.

METHODS

Twenty individuals with fragile X syndrome and 20 individuals with Down syndrome between nine and 22 years of age participated in this study. We coded gesture rate and purpose from an autism spectrum disorder evaluation, the Autism Diagnostic Observation Schedule - Second Edition.

RESULTS

We did not find between-group differences (Down syndrome compared to fragile X syndrome) in gesture rate or purpose. Notably, as autism spectrum disorder symptoms increased, the group with Down syndrome produced a lower rate of gestures, but used gestures for the same purpose. Gesture rate did not change based on autism spectrum disorder symptoms in the participants with fragile X syndrome, but as autism spectrum disorder symptoms increased, the participants with fragile X syndrome produced a larger proportion of gestures to regulate behavior and a smaller proportion for joint attention/social interaction.

CONCLUSIONS

Overall, the amount or purpose of gestures did not differentiate individuals with Down syndrome and fragile X syndrome. However, the presence of autism spectrum disorder symptoms had a significant and unique impact on these genetic disorders. In individuals with Down syndrome, the presence of more autism spectrum disorder symptoms resulted in a reduction in the rate of gesturing, but did not change the purpose. However, in fragile X syndrome, the rate of gestures remained the same, but the purpose of those gestures changed based on autism spectrum disorder symptoms.

IMPLICATIONS

Autism spectrum disorder symptoms differentially impact gestures in Down syndrome and fragile X syndrome. Individuals with Down syndrome and more autism spectrum disorder symptoms are using gestures less frequently. Therefore, clinicians may need to consider children with Down syndrome demonstrating symptoms of autism spectrum disorder as distinctly different from children with Down syndrome and few to no symptoms of autism spectrum disorder when implementing interventions or therapy techniques. Severity of autism spectrum disorder symptoms in fragile X syndrome affects qualitative gesture use and motivation to communicate through social gestures, which may be an appropriate goal to target in children with fragile X syndrome and heightened autism spectrum disorder symptoms.

Boys with fragile X syndrome: investigating temperament in early childhood

BACKGROUND

Fragile X syndrome (FXS) is an x-linked genetic disorder that represents the most common hereditary cause of Intellectual Disability (ID). Very specific behavioural features (e.g. attention deficit hyperactivity disorder and stereotyped behaviour) are associated with FXS in adolescents and adults, yet research on temperament and behavioural characteristics in young children with FXS has been more limited and less conclusive.

METHOD

This study investigated temperament differences in young boys (3-7 years old) with FXS (N = 26) recruited from a national FXS centre and controls (N = 26) matched on age, gender and race.

RESULTS

Compared with controls, boys with FXS exhibited less overall surgency/extraversion and effortful control. Boys with FXS also displayed significantly greater activity and shyness and less attentional focusing, inhibitory control, soothability and high intensity pleasure (tendency to enjoy intense/complex activities), relative to comparison children. A significant interaction between age and diagnosis (FXS or control) was observed for negative affectivity only.

CONCLUSIONS

Attention difficulties commonly found in adolescents and adults with FXS appear to also be characteristic of young boys with FXS, as reflected by lower effortful control. Age-related findings concerning negative affectivity may be particularly significant, leading to improved intervention/preventative efforts.

Programming social behavior by the maternal fragile X protein

The developing fetus and neonate are highly sensitive to maternal environment. Besides the well-documented effects of maternal stress, nutrition and infections, maternal mutations, by altering the fetal, perinatal and/or early postnatal environment, can impact the behavior of genetically normal offspring. Mutation/premutation in the X-linked FMR1 (encoding the translational regulator FMRP) in females, although primarily responsible for causing fragile X syndrome (FXS) in their children, may also elicit such maternal effects. We showed that a deficit in maternal FMRP in mice results in hyperactivity in the genetically normal offspring. To test if maternal FMRP has a broader intergenerational effect, we measured social behavior, a core dimension of neurodevelopmental disorders, in offspring of FMRP-deficient dams. We found that male offspring of Fmr1(+/-) mothers, independent of their own Fmr1 genotype, exhibit increased approach and reduced avoidance toward conspecific strangers, reminiscent of 'indiscriminate friendliness' or the lack of stranger anxiety, diagnosed in neglected children and in patients with Asperger's and Williams syndrome. Furthermore, social interaction failed to activate mesolimbic/amygdala regions, encoding social aversion, in these mice, providing a neurobiological basis for the behavioral abnormality. This work identifies a novel role for FMRP that extends its function beyond the well-established genetic function into intergenerational non-genetic inheritance/programming of social behavior and the corresponding neuronal circuit. As FXS premutation and some psychiatric conditions that can be associated with reduced FMRP expression are more prevalent in mothers than full FMR1 mutation, our findings potentially broaden the significance of FMRP-dependent programming of social behavior beyond the FXS population.

Infant Development in Fragile X Syndrome: Cross-Syndrome Comparisons

This study examined the developmental profile of male infants with fragile X syndrome (FXS) and its divergence from typical development and development of infants at high risk for autism associated with familial recurrence (ASIBs). Participants included 174 boys ranging in age from 5 to 28 months. Cross-sectional profiles on the Mullen Scales of Early Learning indicated infants with FXS could be differentiated from typically developing infants and ASIBs by 6 months of age. Infants with FXS displayed a trend of lower developmental skills with increasing age that was unique from the typically developing and ASIB groups. Findings suggest infants with FXS present with more significant, pervasive and early emerging delays than previously reported with potentially etiologically distinct developmental profiles.

The emergence and stability of attention deficit hyperactivity disorder in boys with fragile X syndrome

BACKGROUND

Children with fragile X syndrome (FXS) are at high risk for developing a range of behavioural disorders, including attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). However, very few studies have investigated the comorbid profile of FXS and ADHD and the possible dissociation from the FXS and ASD profile. The present study examined the relationship of childhood temperament characteristics of the Surgency facet (activity level, impulsivity, approach, shyness, and smiling and laughter) and the severity of ADHD and ASD features at two measurement time points in childhood, preschool (ages 3-4) and at school entry (ages 5-6).

METHODS

The study consisted of males with FXS measured at each time point (preschool and school entry), as well as comparison of typically developing (TD) boys at the preschool measurement time point. Parent reported measures of temperament and behavioural symptoms were collected at each time point. Multiple regression analyses were used to analyse obtained data.

RESULTS

Elevated activity level scores are associated with ADHD scores at preschool age and elevated shyness and decreased smiling and laughter are strongly associated with ADHD scores upon school entry. Impulsivity emerges as a strong indicator of elevated ADHD scores around school age, but even preschool impulsivity scores demonstrate some predictive value for higher ADHD scores later in school. Finally, no Surgency characteristic was significantly related to ASD scores at any age.

CONCLUSIONS

Impulsivity serves as an indicator of elevated ADHD symptoms across development periods in boys with FXS, while activity level is just indicative of higher ADHD scores at the preschool age. The Surgency facet of temperament at either age does not predict strong relationships of comorbid pathologies of ADHD and ASD in FXS. However, Surgency characteristics may serve as informative discriminative factors when studying behavioural outcomes in boys with FXS.

HPA axis function predicts development of working memory in boys with FXS

The present study examines verbal working memory over time in boys with fragile X syndrome (FXS) compared to nonverbal mental-age (NVMA) matched, typically developing (TD) boys. Concomitantly, the relationship between cortisol-a physiological marker for stress-and verbal working memory performance over time is examined to understand the role of physiological mechanisms in cognitive development in FXS. Participants were assessed between one and three times over a 2-year time frame using two verbal working memory tests that differ in complexity: memory for words and auditory working memory with salivary cortisol collected at the beginning and end of each assessment. Multilevel modeling results indicate specific deficits over time on the memory for words task in boys with FXS compared to TD controls that is exacerbated by elevated baseline cortisol. Similar increasing rates of growth over time were observed for boys with FXS and TD controls on the more complex auditory working memory task, but only boys with FXS displayed an association of increased baseline cortisol and lower performance. This study highlights the benefit of investigations of how dynamic biological and cognitive factors interact and influence cognitive development over time.

Symptoms of Autism in Males with Fragile X Syndrome: A Comparison to Nonsyndromic ASD Using Current ADI-R Scores

Symptoms of autism are frequent in males with fragile X syndrome (FXS), but it is not clear whether symptom profiles differ from those of nonsyndromic ASD. Using individual item scores from the Autism Diagnostic Inventory-Revised, we examined which current symptoms of autism differed in boys with FXS relative to same-aged boys diagnosed with nonsyndromic ASD. In addition, different subsamples of participants were matched on autism diagnostic status and severity of autism symptoms. Between-group comparisons revealed that boys with FXS showed significantly less impairment in Social Smiling than did age-, diagnostic-, and severity-matched boys with nonsyndromic ASD. Severity-matched boys with FXS showed more impairment in complex mannerisms than did boys with nonsyndromic ASD. Behavioral differences between FXS and nonsyndromic ASD may be of theoretical importance in understanding the causes and correlates of ASD in FXS and in developing and implementing appropriate treatments.

Autism Symptomatology in Boys with Fragile X Syndrome: A Cross Sectional Developmental Trajectories Comparison with Nonsyndromic Autism Spectrum Disorder

Although males with fragile X syndrome (FXS) are frequently described as demonstrating autism symptomatology, there is much debate regarding whether the behavioral symptoms representing the core domains of autism are the result of the same or different underlying neurological/psychological mechanisms. The present study used a cross-sectional developmental trajectories approach to compare the profiles of autism symptomatology relative to chronological age (CA), nonverbal IQ, and expressive vocabulary ability between individuals with FXS and individuals with nonsyndromic ASD. Results suggest that the onset of autism symptoms and their developmental trajectories in males with FXS differ in important ways as a function of CA, nonverbal cognitive ability, and expressive vocabulary relative to males with nonsyndromic ASD. Theoretical and clinical implications are discussed.

Do Children With Fragile X Syndrome Show Declines or Plateaus in Adaptive Behavior?

This study explores if children with fragile X syndrome (FXS) show advances, declines, or plateaus in adaptive behavior over time and the relationship of nonverbal cognitive abilities and autistic behavior on these trajectories. Parents of 55 children with FXS completed the Vineland Adaptive Behavior Scales ( Sparrow, Balla, & Cicchetti, 1984 ; Sparrow, Cicchetti, & Balla, 2005 ) between 3 and 6 times from 2 to 10 years of age. Using raw scores, results indicate that about half of the sample showed advances in adaptive behavior, whereas the other half showed declines, indicating a regression in skills. Children who were more cognitively advanced and had less autistic behaviors had higher trajectories. Understanding the developmental course of adaptive behavior in FXS has implications for educational planning and intervention, especially for those children showing declines.

Early identification and intervention services for children with autism in Vietnam

BACKGROUND

In high income countries in Europe and North America, early identification and intervention for autism spectrum disorders (ASD) have been linked to improved long-term outcomes. However, in most low and middle income countries (LMIC) little is known about use or availability of such services, which limits the ability of policy and development planning. The purpose of the present study was assess the use of ASD services in Vietnam, an Asian LMIC, in order to identify areas within the field that should be specifically targeted to improve ASD services in Vietnam.

METHODS

Surveys were conducted in six different cities across Vietnam with 90 parents/caregivers of children with ASD, 115 professionals working with children with ASD, and 10 directors of agencies providing ASD services. Parents/caregivers' survey assessed demographics and information regarding their child's symptoms and services the child received. Professionals' survey assessed their demographic and professional background, the ASD services they provide, and their perspective on the quality of ASD services at their agency. Directors' survey included these same questions as well as additional questions regarding the operation of the agency.

RESULTS

Early identification and intervention ASD services are available in Vietnam, at least in major cities. However, there is a lack of well-trained professionals, the tools used for evaluation and diagnosis are limited, outdated and unstandardized, and the quality of services is questionable. Most importantly, a scientific evidence base for services is absent, and the country lacks an official governmental policy for supporting children with ASD.

CONCLUSIONS

Research directly assessing the quality of ASD services in Vietnam is needed. Most centrally, efforts at facilitating governmental policy and support advocacy are needed to increase the likelihood that families and children with ASD will receive appropriate and effective services.

DSM-5 changes and the prevalence of parent-reported autism spectrum symptoms in Fragile X syndrome

We used survey methodology to assess parent-reported autism symptomology in 758 individuals (639 males; 119 females) with fragile X syndrome (FXS). Caregivers reported whether their child with FXS had been diagnosed with an autism spectrum disorder (ASD) and endorsed symptoms based on a list of observable behaviors related to ASD diagnoses. Symptom counts were categorized based on DSM-IV-TR and DSM-5 criteria. Based on behavioral symptoms endorsed by caregivers, 38.7 % of males and 24.7 % of females met criteria for DSM-IV-TR diagnosis of autistic disorder. Significantly fewer males (27.8 %) and females (11.3 %) met criteria for ASD based on DSM-5 criteria. Although 86.4 % of males and 61.7 % of females met criteria for the restricted and repetitive behavior domain for DSM-5, only 29.4 % of males and 13.0 % of females met criteria for the social communication and interaction (SCI) domain. Relaxing the social communication criteria by one symptom count led to a threefold increase in those meeting criteria for ASD, suggesting the importance of subthreshold SCI symptoms for individuals with FXS in ASD diagnoses. Findings suggest important differences in the way ASD may be conceptualized in FXS based on the new DSM-5 criteria.

Autism Spectrum Disorder (ASD) and Fragile X Syndrome (FXS): Two Overlapping Disorders Reviewed through Electroencephalography-What Can be Interpreted from the Available Information?

Autism Spectrum Disorder (ASD) and Fragile X syndrome (FXS) are neurodevelopmental disorders with different but potentially related neurobiological underpinnings, which exhibit significant overlap in their behavioural symptoms. FXS is a neurogenetic disorder of known cause whereas ASD is a complex genetic disorder, with both rare and common genetic risk factors and likely genetic and environmental interaction effects. A comparison of the phenotypic presentation of the two disorders may highlight those symptoms that are more likely to be under direct genetic control, for example in FXS as opposed to shared symptoms that are likely to be under the control of multiple mechanisms. This review is focused on the application and analysis of electroencephalography data (EEG) in ASD and FXS. Specifically, Event Related Potentials (ERP) and resting state studies (rEEG) studies investigating ASD and FXS cohorts are compared. This review explores the electrophysiological similarities and differences between the two disorders in addition to the potentially associated neurobiological mechanisms at play. A series of pertinent research questions which are suggested in the literature are also posed within the review.

Parent-reported temperament trajectories among infant siblings of children with autism

Temperament atypicalities have been documented in infancy and early development in children who develop autism spectrum disorders (ASD). The current study investigates whether there are differences in developmental trajectories of temperament between infants and toddlers with and without ASD. Parents of infant siblings of children with autism completed the Carey Temperament Scales about their child at 6, 12, 18, 24, and 36 months of age. Temperament trajectories of children with ASD reflected increases over time in activity level, and decreasing adaptability and approach behaviors relative to high-risk typically developing (TD) children. This study is the first to compare temperament trajectories between high-risk TD infants and infants subsequently diagnosed with ASD in the developmental window when overt symptoms of ASD first emerge.

Transdiagnostic Case Conceptualization of Emotional Problems in Youth with ASD: An Emotion Regulation Approach

Youth with autism spectrum disorder often struggle to cope with co-occurring anxiety, depression, or anger, and having both internalizing and externalizing symptoms is a common clinical presentation. A number of authors have designed cognitive-behavioral interventions to address transdiagnostic factors related to multiple emotional problems, although none have applied this focus to youth with ASD. The current review article describes how a transdiagnostic emotion regulation framework may inform cognitive-behavioral interventions for youth with ASD, which until now have focused almost exclusively on anxiety. Research is needed to empirically test how a transdiagnostic intervention can address the processes of emotion regulation and assist youth with ASD to cope with their emotional disorders.

The fragile X syndrome-autism comorbidity: what do we really know?

Autism spectrum disorder (ASD) is a common comorbid condition in people with fragile X syndrome (FXS). It has been assumed that ASD symptoms reflect the same underlying psychological and neurobiological impairments in both FXS and non-syndromic ASD, which has led to the claim that targeted pharmaceutical treatments that are efficacious for core symptoms of FXS are likely to be beneficial for non-syndromic ASD as well. In contrast, we present evidence from a variety of sources suggesting that there are important differences in ASD symptoms, behavioral and psychiatric correlates, and developmental trajectories between individuals with comorbid FXS and ASD and those with non-syndromic ASD. We also present evidence suggesting that social impairments may not distinguish individuals with FXS with and without ASD. Finally, we present data that demonstrate that the neurobiological substrates of the behavioral impairments, including those reflecting core ASD symptoms, are different in FXS and non-syndromic ASD. Together, these data suggest that there are clinically important differences between FXS and non-syndromic ASD that are masked by reliance on the categorical diagnosis of ASD. We argue for use of a symptom-based approach in future research, including studies designed to evaluate treatment efficacy.

Consistency between research and clinical diagnoses of autism among boys and girls with fragile X syndrome

BACKGROUND

Prior research suggests that 60-74% of males and 16-45% of females with fragile X syndrome (FXS) meet criteria for autism spectrum disorder (ASD) in research settings. However, relatively little is known about the rates of clinical diagnoses in FXS and whether such diagnoses are consistent with those performed in a research setting using gold standard diagnostic tools.

METHOD

This study explored whether boys and girls with FXS met criteria for ASD in a research setting using the Autism Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview-Revised (ADI-R), and then compared these data with the frequency of parent-reported clinical diagnoses. We also examined child and family characteristics as potential diagnostic predictors across settings. Participants included 35 females and 51 males with FXS (mean age: 10 years), who were from Eastern and Midwestern regions of the USA.

RESULTS

About half of the children met criteria for ASD on either the ADOS or ADI-R, with ASD occurring three times more frequently in males than females (∼75% vs. ∼25%). In contrast, ∼25% of participants of both genders had received a clinical diagnosis of ASD. While cognitive and language skills predicted diagnostic outcome on the ADOS and ADI-R, these skills did not predict clinical diagnoses. Executive functions predicted clinical diagnoses, but not diagnoses per the ADOS or ADI-R.

CONCLUSIONS

ASD in FXS may be under-diagnosed in clinical/educational settings, which raises questions regarding access to ASD-related services.

Stereological study of the neuronal number and volume of 38 brain subdivisions of subjects diagnosed with autism reveals significant alterations restricted to the striatum, amygdala and cerebellum

Introduction

A total of 38 brain cytoarchitectonic subdivisions, representing subcortical and cortical structures, cerebellum, and brainstem, were examined in 4- to 60-year-old subjects diagnosed with autism and control subjects (a) to detect a global pattern of developmental abnormalities and (b) to establish whether the function of developmentally modified structures matches the behavioral alterations that are diagnostic for autism. The volume of cytoarchitectonic subdivisions, neuronal numerical density, and total number of neurons per region of interest were determined in 14 subjects with autism and 14 age-matched controls by using unbiased stereological methods.

Results

The study revealed that significant differences between the group of subjects with autism and control groups are limited to a few brain regions, including the cerebellum and some striatum and amygdala subdivisions. In the group of individuals with autism, the total number and numerical density of Purkinje cells in the cerebellum were reduced by 25% and 24%, respectively. In the amygdala, significant reduction of neuronal density was limited to the lateral nucleus (by 12%). Another sign of the topographic selectivity of developmental alterations in the brain of individuals with autism was an increase in the volumes of the caudate nucleus and nucleus accumbens by 22% and 34%, respectively, and the reduced numerical density of neurons in the nucleus accumbens and putamen by 15% and 13%, respectively.

Conclusions

The observed pattern of developmental alterations in the cerebellum, amygdala and striatum is consistent with the results of magnetic resonance imaging studies and their clinical correlations, and of some morphometric studies that indicate that detected abnormalities may contribute to the social and communication deficits, and repetitive and stereotypical behaviors observed in individuals with autism.

Maternal predictors of anxiety risk in young males with fragile X

Children with fragile X syndrome (FXS) demonstrate high rates of anxiety disorders, with 65-83% meeting diagnostic criteria. The severity of anxiety symptoms in FXS has been shown to be partially predicted by elevated negative affect across early childhood [Tonnsen et al. (2013a); J Abnorm Child Psychol 41:267-280]. This association suggests that biologically driven vulnerability emerges early in development, as is reported in non-clinical populations. However, anxiety emergence is likely moderated by multifaceted genetic, biological and environmental risk and protective factors. Mothers with the FMR1 premutation have been shown to exhibit elevated parenting stress and internalizing symptoms, which have each been associated with child behavior problems [Bailey et al. (2008a); Am J Med Genet Part A 146A:2060-2069 and Bailey et al. (2008b) Am J Med Genet Part A 146A:720-729]. Despite these findings, it is unclear whether maternal factors directly relate to anxiety vulnerability in high-risk children with FXS, a question essential to informing targeted, family-sensitive treatment. The present study examines how maternal protective and risk factors relate to child inhibition reflected in (1) child anxiety symptoms, (2) child trajectories of negative affect, and (3) the association between child anxiety and negative affect. Primary predictors include maternal parenting stress, indicators of mental health risk (anxiety and depressive symptoms), and maternal optimism. We also examine genetic correlates in mothers (CGG repeats, activation ratio, mRNA). Our findings suggest that behavioral inhibition in young children with FXS is associated with higher parenting stress and lower optimism, and higher parenting stress is associated with lower maternal X-activation ratio. These findings underscore the need for family-sensitive treatment strategies for anxiety disorders in children with FXS.