State-of-the-art therapies for fragile X syndrome

Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by a full mutation (> 200 CGG repeats) in the FMR1 gene. FXS is the leading cause of inherited intellectual disabilities and the most commonly known genetic cause of autism spectrum disorder. Children with FXS experience behavioral and sleep problems, anxiety, inattention, learning difficulties, and speech and language delays. There are no approved medications for FXS; however, there are several interventions and treatments aimed at managing the symptoms and improving the quality of life of individuals with FXS. A combination of non-pharmacological therapies and pharmacotherapy is currently the most effective treatment for FXS. Currently, several targeted treatments, such as metformin, sertraline, and cannabidiol, can be used by clinicians to treat FXS. Gene therapy is rapidly developing and holds potential as a prospective treatment option. Soon its efficacy and safety in patients with FXS will be demonstrated. WHAT THIS PAPER ADDS: Targeted treatment of fragile X syndrome (FXS) is the best current therapeutic approach. Gene therapy holds potential as a prospective treatment for FXS in the future.

Exploring the feasibility of collecting multimodal multiperson assessment data via distance in families affected by fragile X syndrome

INTRODUCTION

Telehealth is an important tool in helping to provide services for hard-to-reach populations. One population that might benefit from telehealth are individuals with fragile X syndrome (FXS). Although FXS is the leading inherited cause of intellectual disability, it is nonetheless a low incidence disorder. Individuals with FXS and their families are involved in research studies, clinical trials and receive interventions - many of which are only offered in a few locations in the United States and thus, not easily accessible to many families. The current project explored the feasibility of using telehealth procedures to collect multimodal behavioural and psychological assessment data from these families.

METHODS

Participation in the current study involved online surveys, measures of physiological indices of stress, live interviews and observations of mother-child interactions conducted via distance videoconferencing using the family's own technology when possible. Across all modes of data collection, we obtained information regarding the feasibility of participating entirely via distance by documenting missing data as well as each mother's overall impression of participating via distance.

RESULTS

Our telehealth procedures were successfully implemented across a wide range of technology platforms with limited difficulty, and we documented little missing data due to technology-related challenges. Perhaps most importantly, however, our sample of mothers reported high satisfaction with participating via distance.

DISCUSSION

These findings suggest that a wide range of services and types of assessments may be amenable to telehealth procedures. Further, the findings have immediate applications as the field shifts towards telehealth due to the coronavirus disease 2019 (COVID-19) pandemic.

Cluttering in the Speech of Young Men With Fragile X Syndrome

PURPOSE

Cluttering is a fluency disorder that has been noted clinically in individuals with fragile X syndrome (FXS). Yet, cluttering has not been systematically characterized in this population, hindering identification and intervention efforts. This study examined the rates of cluttering in male young adults with FXS using expert clinical opinion, the alignment between expert clinical opinion and objectively quantified features of cluttering from language transcripts, and the association between cluttering and aspects of the FXS phenotype.

METHOD

Thirty-six men with FXS (aged 18-26 years; M = 22, SD = 2.35) contributed language samples and completed measures of nonverbal cognition, autism symptoms, anxiety, and symptoms of attention-deficit/hyperactivity disorder (ADHD). The presence of cluttering was determined by the consensus of two clinical experts in fluency disorders based on characteristics exhibited in the language sample. Cluttering features (speech rate, disfluencies, etc.) were also objectively quantified from the language transcripts.

RESULTS

Clinical experts determined that 50% of participants met the criteria for a cluttering diagnosis. Phrase repetitions were the most salient feature that distinguished individuals who cluttered. Although the presence of cluttering was not associated with autism symptoms or mean length of utterance, cluttering was more likely to occur when nonverbal cognitive ability was higher, ADHD symptoms were elevated, and anxiety symptoms were low.

CONCLUSIONS

Half of the male young adults with FXS exhibited cluttering, which supports FXS as a genetic diagnosis that is highly enriched for risk of cluttering. Cluttering was associated with increased ADHD symptoms and cognitive ability and reduced anxiety symptoms. This study contributes a new description of the clinical presentation of cluttering in men with FXS and may lead to improved understanding of the potential underlying mechanisms of cluttering and eventual refinements to treatment and diagnosis.

Responsive Parenting as a Target for Telehealth Language Interventions in Fragile X Syndrome: Implications for Scalability and Best Practices

This review highlights the ways in which telehealth procedures can be implemented to help bridge the research-to-practice gap in supporting developmental outcomes for youth with fragile X syndrome (FXS). We review how the literature to date has informed potential treatment targets in the areas of speech and language development with a focus on understanding and supporting the dyadic relationship between the child and their biological mother, who is also impacted biologically. Notably, parental responsivity is an area that is strongly related to child language outcomes, both early and into adolescence, and thus, it is an important treatment target for subsequent interventions. To date, several parent-implemented interventions have been done in FXS across a broad age range (2-17-year-olds) all showing support not only that parents are successful in learning responsive strategies but also that there are subsequent impacts to child language development. Moreover, these interventions were successfully implemented at a distance through telehealth procedures including video teleconferencing and shared recordings of parent-child interactions. This review also addresses potential moderators of treatment gains. Implications for scaling such interventions in the future as well as best practices for incorporating telehealth procedures into future research and intervention programs are also discussed.

Conocimientos sobre Síndrome de X Frágil de los maestros de audición y lenguaje y los logopedas de la Región de Murcia

El síndrome de X Frágil (SXF) es la primera causa de discapacidad intelectual de origen hereditario y la segunda de origen genético después del síndrome de Down. Se produce por una mutación en el gen FMR1 en el brazo largo del cromosoma X. Su fenotipo es muy variado, presentando rasgos físicos característicos, junto con problemas de conducta, relacionados con hiperactividad y ansiedad social. Un área habitualmente afectada durante el desarrollo del niño es el lenguaje, en todas sus dimensiones, mostrándose rasgos propios en cada una de ellas. Por ello, estos niños siempre son atendidos por logopedas y maestros de audición y lenguaje, en los que sería deseable un amplio conocimiento de las características del síndrome. En este trabajo se analiza si los profesionales del lenguaje poseen esos conocimientos. Para ello se diseñó un instrumento para recabar información sobre formación y experiencia con SXF y evaluar el conocimiento del profesional en algunas de sus características más habituales. El instrumento lo cumplimentaron, voluntariamente vía online, 35 maestros de audición y lenguaje y 49 logopedas. Se compararon los resultados de ambos grupos profesionales en función de variables como experiencia previa con el SXF o formación sobre él. Ambos grupos de profesionales presentan carencias importantes en sus conocimientos sobre esas características del SXF, no encontrándose diferencias significativas entre maestros y logopedas. Además, se constata que la formación recibida mejora el conocimiento sobre el SXF.

Parent Perspectives on Augmentative and Alternative Communication Integration for Children With Fragile X Syndrome: It Starts in the Home

Many children with fragile X syndrome (FXS) have complex communication needs and may benefit from augmentative and alternative communication (AAC). This qualitative study explored how four mother-child dyads used AAC in the home. Data were collected using participant observations, open-ended interviews, and record reviews, and analyzed using grounded theory methods. Findings revealed that mothers found AAC to be a useful tool for addressing their children's complex communication needs, but practical and personal factors impacted its use in the home. This study sheds light on how mothers of children with FXS view and utilize AAC as a way to promote communication at home. Understanding parental perspectives can help to guide professionals in planning appropriate AAC interventions specific to FXS.

A single episode of early-life status epilepticus impacts neonatal ultrasonic vocalization behavior in the Fmr1 knockout mouse

Fragile X syndrome (FXS) is a genetic disorder caused by a trinucleotide (CGG) expansion mutation in the Fmr1 gene located on the X chromosome. It is characterized by hyperactivity, increased anxiety, repetitive-stereotyped behaviors, and impaired language development. Many children diagnosed with FXS also experience seizures during their lifetime. However, the underlying etiology of the relationship between FXS and epilepsy is not fully understood. Ultrasonic vocalizations (UVs) are one tool that may be used to measure early behavioral changes in mouse pups. In the present study, neonatal UVs were analyzed as a measure of communicative behavior in a mouse model of FXS, both with and without early-life seizures (ELSs). On postnatal day (PD) 10, status epilepticus (SE) was induced via intraperitoneal injections of 0.5% kainic acid (2.0 mg/kg) in male Fmr1 knockout (KO) and wild-type (WT) mice. On PD 12, all pups were temporarily isolated from their dam and UVs were recorded. Significant alterations were found in both spectral and temporal measures across genotype and seizure groups. Early-life seizure experience resulted in a significant increase in the quantity of UVs only in WT animals (p < 0.05). We also found that while there was no difference between genotypes in the total number of vocalizations made, calls produced by Fmr1 KO mice were significantly shorter and had a higher peak frequency compared with WT mice. Overall, these findings support the use of vocalization behavior as an early phenotypic marker and highlight the importance of utilizing double-hit models to better understand comorbid disorders.

Evaluating Social Interactions Using the Autism Screening Instrument for Education Planning-3rd Edition (ASIEP-3): Interaction Assessment in Children and Adults with Fragile X Syndrome

An efficient and direct measure of social interactions and autism symptoms is needed for fragile X syndrome (FXS) research and clinical care. The Autism Screening Instrument for Educational Planning-Third Edition (ASIEP-3) Interaction assessment is a brief standardized measure that quantifies social responses under different conditions. The feasibility and validity of the ASIEP-3 was evaluated in 26 males and 13 females with FXS, along with cognitive testing and behavior questionnaires. The videos were scored at 10-second intervals, and the observed behaviors were scored as an interaction, independent play, no response, or aggression. In total, 39/41 participants successfully completed the ASIEP-3 (age M = 14.4 ± 10.2), with a range of cognitive abilities (abbreviated IQ (ABIQ) M = 58.9 ± 17.3, median = 50), behaviors (Aberrant Behavior Checklist (ABC) Total M = 37.00 ± 27.3), and autism diagnoses (N = 22/39). Reliable administration was demonstrated by all team members. The mean coded behaviors included interaction (40.6%), independent play (36.8%), no response (21.1%), and aggressive behavior (<10%). The interaction score was negatively correlated with the Social Communication Questionnaire (SCQ) score (p = 0.037), and the profiles differed by autism spectrum disorder (ASD) diagnosis. The intraclass correlation coefficients (ICCs) ranged from 0.79 to 0.93 for master's level and above. Administration of the ASIEP-3 was feasible for FXS across sex, age, ability, and behavior ratings by a trained research team. Reliable scoring required advanced training in the assessment of social development and FXS experience. The scores correlated to ratings and diagnoses of ASD. The ASIEP-3 shows promise to reliably index social interactions in FXS.

Mobile technology use and skills among individuals with fragile X syndrome: implications for healthcare decision making

BACKGROUND

Little is known about how individuals with fragile X syndrome (FXS) and their families use technology in daily life and what skills individuals with FXS can perform when using mobile technologies.

METHODS

Using a mixed-methods design, including an online survey of parents (n = 198) and a skills assessment of individuals with FXS (n = 6), we examined the experiences and abilities of individuals with FXS for engaging with mobile technology.

RESULTS

Parents reported that individuals with FXS often used technology in their daily lives, with variations based on age of child, sex, autism status, depression, and overall ability. Parents frequently sought and shared FXS-related information online. Assessment data revealed that individuals with FXS demonstrated proficiency in interacting with technology.

CONCLUSIONS

Mobile technology is a tool that can be used in FXS to build skills and increase independence rather than simply for recreational purposes. Implications for using mobile technology to enhance healthcare decision making are discussed.

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.

Spectral and temporal properties of calls reveal deficits in ultrasonic vocalizations of adult Fmr1 knockout mice

The Fmr1 knockout (KO) mouse has commonly been used to investigate communication impairments, one of the key diagnostic symptoms observed in Fragile X syndrome (FXS) and Autism spectrum disorder (ASD). Many studies have found alterations in ultrasonic vocalizations (USVs) in neonatal Fmr1 KO mice, however, there is limited research investigating whether these deficits continue into adulthood. In the present study, we examine differences in female urine-induced ultrasonic vocalizations, scent marking behavior, odor discrimination, and open field activity in adult male Fmr1 KO and wildtype (WT) mice. Overall, we found extensive alterations between genotypes in both spectral and temporal properties of ultrasonic vocalizations. There was no difference in the average number of calls emitted by both genotypes, however, Fmr1 KO mice emitted calls of a higher frequency, decreased amplitude, and shorter duration than WT mice. Spectrographic analyses revealed statistically significant differences between genotypes in the types of calls emitted. Contrastingly, we found no differences in scent marking behavior, a form of social communication, or in odor discrimination and activity levels of the mice. The results corroborate previous studies emphasizing the importance of qualitative differences observed in vocalization behavior of Fmr1 KO mice, rather than quantitative measurements such as number of calls emitted. Overall, the study confirms the presence of abnormalities in vocalization behavior in adult Fmr1 KO mice that we believe are consistent with communication deficits seen in the syndrome.

Assistive technology to promote occupation and reduce mouthing by three boys with fragile X syndrome

OBJECTIVES

To extend the use of assistive technology (AT) for promoting a new adaptive response and to reduce hand mouthing, by three boys with fragile X syndrome. To monitor the effects of the intervention program on the positive mood. To carry out a three month follow-up phases. To conduct a social validation assessment involving 30 parents of children who presented multiple disabilities as raters.

METHODS

The study was implemented according to an ABAB experimental design, where A represented baseline phases (technology available but inactive) and B represented intervention phases (the technology ensured 7 s of positive stimulation).

RESULTS

All participants improved and consolidated their performance. Parents involved in the social validation assessment rated positively the use of such technology.

CONCLUSION

AT-based program was useful, affordable, and effective for enhancing constructive engagement, self-determination, and for improving quality of life by children with fragile X syndrome and severe to profound developmental disabilities.

Characterization of ultrasonic vocalizations of Fragile X mice

Fragile X Syndrome (FXS) is the leading form of inherited intellectual disability. It is caused by the transcriptional silencing of FMR1, the gene which codes for the Fragile X Mental Retardation Protein (FMRP). Patients who have FXS exhibit numerous behavioral and cognitive impairments, such as attention-deficit/hyperactivity disorder, obsessive compulsive disorder, and autistic-like behaviors. In addition to these behavioral abnormalities, FXS patients have also been shown to exhibit various deficits in communication such as abnormal sentence structures, increased utterances, repetition of sounds and words, and reduced articulation. These deficits can dramatically hinder communication for FXS patients, exacerbating learning and cognition impairments while decreasing their quality of life. To examine the biological underpinnings of these communication abnormalities, studies have used a mouse model of the Fragile X Syndrome; however, these vocalization studies have resulted in inconsistent findings that often do not correlate with abnormalities observed in FXS patients. Interestingly, a detailed examination of frequency modulated vocalizations that are believed to be a better assessment of rodent communication has never been conducted. The following study used courtship separation to conduct a detailed examination of frequency modulated ultrasonic vocalizations (USV) in FXS mice. Our analyses of frequency modulated USVs demonstrated that adult FXS mice exhibited longer phrases and more motifs. Phrases are vocalizations consisting of multiple frequency modulated ultrasonic vocalizations, while motifs are repeated frequency modulated USV patterns. Fragile X mice had a higher proportion of "u" syllables in all USVs and phrases while their wildtype counterparts preferred isolated "h" syllables. Although the specific importance of these syllables towards communication deficits still needs to be evaluated, these findings in production of USVs are consistent with the repetitive and perseverative speech patterns observed in FXS patients. This study demonstrates that FXS mice can be used to study the underlying biological mechanism(s) mediating FXS vocalization abnormalities.

Learning computer ethics and social responsibility with tabletop role-playing games

Purpose

– Tabletop online role-playing games enable active learning appropriate for different ages and learner capabilities. They have also been implemented in computer and engineering ethics courses. The paper aims to discuss these issues.

Design/methodology/approach

– This paper presents the experience of implementing role-playing in several courses embedded in Web 2.0 environment, with an intention to confront complex and sometimes mutually conflicting concepts, and integrate them into a whole.

Findings

– Typical examples introducing two basic scenarios representing individual and collaborative learning scripts are presented together with the detailed analysis how the games were performed, the effort to participate in, and to maintain them. Particular attention is paid to student feedback.

Originality/value

– The paper concludes with the basic findings of the effects of role-playing in current learning computer ethics and social responsibilities courses, and recommendations for future implementation of similar asynchronous learning online activities in order to increase their academic value and prepare students for their forthcoming professional integration.

Functional skills of individuals with fragile x syndrome: a lifespan cross-sectional analysis

Parents of 1,105 male and 283 female children with fragile X syndrome described functional skill attainment in eating, dressing, toileting, bathing/hygiene, communication, articulation, and reading. The majority of adult children had mastered many skills independently. Most adults were verbal, used the toilet, dressed, ate independently, bathed, and used a towel independently. However, some skills were not as well-developed, such as using complex sentences, reading, or speaking at a typical rate. As expected, significant differences were found between males and females. The findings highlight major skill attainments, identify skills that should be the target of specific intervention programs, suggest variable trajectories to be tested more precisely through direct assessments and longitudinally, and provide baseline data for treatment studies.

Early temperament and negative reactivity in boys with fragile X syndrome

BACKGROUND

The phenotype of children and adults with fragile X syndrome (FXS) includes a number of problem behaviours such as inattention, social anxiety and aggressive outbursts. However, very little work has been conducted with young children with FXS less than 5 years of age to examine the developmental pathway of problem behaviours in this population and to determine if later occurring problem behaviours may be rooted in early appearing temperament profiles.

METHODS

Parent ratings and laboratory-based behavioural observations of negative reactivity were examined in 25 3-year-old boys with FXS and compared with 64 typically developing boys matched on age.

RESULTS

Compared with the typically developing group, boys with FXS were rated by their parents as exhibiting less anger and sadness on the Child Behaviour Questionnaire (CBQ), and they showed less facial sadness on the Laboratory Temperament Assessment Battery (Lab-TAB). No group differences were found on the Lab-TAB measures of distress vocalisations, bodily struggle, and facial anger; and anger peaked in the middle of the arm restraint episode for both groups. For boys with FXS, mental age was moderately positively correlated, and autistic behaviour was moderately negatively correlated, with sadness scores from the CBQ.

CONCLUSIONS

Our results show different behavioural profiles in very young children with FXS than reported in older-aged children with FXS which implies that temperamental differences and elevated problem behaviours reported in older-aged children with FXS may not be rooted in early temperament. This information is important to develop the phenotype of early development in FXS to facilitate early identification and treatment.

Speech fluency in fragile X syndrome

The present study investigated the dysfluencies in the speech of nine French speaking individuals with fragile X syndrome. Type, number, and loci of dysfluencies were analysed. The study confirms that dysfluencies are a common feature of the speech of individuals with fragile X syndrome but also indicates that the dysfluency pattern displayed is not identical to developmental stuttering. To what extent the pattern of dysfluency in individuals with fragile X syndrome is syndrome specific is not yet clear.

Language phenotypes and intervention planning: bridging research and practice

This paper focuses on the communication and language phenotypes associated with three genetic disorders: Down syndrome, Williams syndrome, and fragile X syndrome. It is argued that there is empirical evidence that these disorders predispose children to specific profiles of strength and weakness in some areas of speech, language, and communication, and that intervention planning for children with each syndrome may take an approach informed by these profiles. Issues related to within-group variability, shared outcomes among syndromes, and the need for empirical validation for syndrome-specific recommendations are discussed.

Discourse skills of boys with fragile X syndrome in comparison to boys with Down syndrome

PURPOSE

This study compared the conversational discourse skills of boys who have fragile X syndrome with and without autism spectrum disorder (ASD) with those of boys with Down syndrome and boys who are typically developing.

METHOD

Participants were boys who have fragile X syndrome with (n = 26) and without (n = 28) ASD, boys with Down syndrome (n = 29), and boys who are typically developing (n = 22). Turns during an examiner-child interaction consisting of structured and semistructured activities were coded for the boys' ability to maintain a topic of conversation and the frequency of perseveration.

RESULTS

The results revealed that boys who had both fragile X and ASD produced significantly more noncontingent discourse than did boys who had only fragile X, boys with Down syndrome, or typically developing boys. This finding was observed regardless of whether the topic was maintained or changed and whether the turn type was a response or initiation. Regardless of autism status, boys with fragile X used more perseveration than did boys in the other groups.

CONCLUSION

These findings suggest that some aspects of the conversational discourse difficulties attributed to fragile X syndrome may be a function of the high rate of comorbidity between fragile X and autism, whereas some difficulties may be characteristic of fragile X syndrome.

ADHD symptoms in children with FXS

Parent- and teacher-report of attention-deficit/hyperactivity disorder (ADHD) symptoms were examined using problem behavior and DSM-IV symptom inventory questionnaires for 63 children with full mutation fragile X syndrome (FXS) and 56 children without disabilities matched on mental age (MA). Prevalence rates of ADHD symptoms varied depending on type of measure (problem behavior or DSM-IV criteria), subscale (ADHD-inattentive or ADHD-hyperactive), scoring method (continuous T-scores or categorical scores based on DSM-IV algorithm), and rater (parent or teacher). Overall, 54-59% of boys with FXS met diagnostic behavioral criteria for either ADHD-inattentive type only, ADHD-hyperactive type only, or ADHD-combined type based on parent or teacher report. Boys with FXS were rated as having clinically high scores or met diagnostic criteria at higher rates than expected for the general population and had higher raw scores than their MA-matched peers. Parent ratings of boys with FXS resulted in higher ADHD-inattentive type and ADHD-hyperactive type T-scores than teachers. Boys who were rated as meeting DSM-IV criteria were more likely to be taking psychotropic medication and to have younger mental ages. Parents were substantially more likely than teachers to rate boys as meeting DSM-IV criteria for ADHD-inattentive type, while teachers were only slightly more likely than parents to rate boys as meeting DSM-IV criteria for ADHD-hyperactive type. Teachers were more likely than parents to rate boys as meeting DSM-IV criteria for ADHD when boys had lower levels of FMRP.

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.

Temperament and vagal tone in boys with fragile X syndrome

Physiological hyperarousal, an elevated state of physiological arousal and poor modulation, has been postulated to be a significant source of behavior problems in children with fragile X syndrome (FXS). Temperament has been associated with behavior problems and may also reflect biological reactivity. Young boys with FXS display poorly modulated and low levels of vagal tone (Roberts, Dev Psychobiol 2001;39:107-123) and high activity, poor attention, low adaptability, poor persistence, and low intensity when compared with a reference sample of typically developing (Hatton, Dev Med Child Neurol 1991;41:625-632). In this study, we integrated physiological indices of vagal tone with temperament ratings and compared a sample of 29 young boys with FXS to 31 typically developing boys matched on chronological age and ethnicity. Boys with FXS were more active, less adaptable, and less persistent than the comparison group. Boys with FXS also showed lower baseline levels and less suppression of vagal tone in response to changing task demands. A relationship between baseline vagal tone and persistence was shown across both groups. However, group differences in temperament dimensions did not appear to be mediated or moderated by vagal tone.