Development of Two Dimensional Measures of Restricted and Repetitive Behavior in Parents and Children

Measuring self and informant perspectives of Restricted and Repetitive Behaviours (RRBs): psychometric evaluation of the Repetitive Behaviours Questionnaire-3 (RBQ-3) in adult clinical practice and research settgs

BACKGROUND

Brief questionnaires that comprehensively capture key restricted and repetitive behaviours (RRBs) across different informants have potential to support autism diagnostic services. We tested the psychometric properties of the 20-item Repetitive Behaviours Questionnaire-3 (RBQ-3), a questionnaire that includes self-report and informant-report versions enabling use across the lifespan.

METHOD

In Study 1, adults referred to a specialised adult autism diagnostic service (N = 110) completed the RBQ-3 self-report version, and a relative or long-term friend completed the RBQ-3 informant-report version. Clinicians completed the abbreviated version of the Diagnostic Interview for Social and Communication Disorders (DISCO-Abbreviated) with the same adults as part of the diagnostic process. For half of the assessments, clinicians were blind to the RBQ-3 ratings. We tested internal consistency, cross-informant reliability and convergent validity of the RBQ-3. In Study 2, a follow-up online study with autistic (N = 151) and non-autistic (N = 151) adults, we further tested internal consistency of the RBQ-3 self-report version. We also tested group differences and response patterns in this sample.

RESULTS

Study 1 showed good to excellent internal consistency for both self- and informant-report versions of the RBQ-3 (total score, α = 0.90, ω = 0.90, subscales, α = 0.76-0.89, ω = 0.77-0.88). Study 1 also showed cross-informant reliability as the RBQ-3 self-report scores significantly correlated with RBQ-3 informant-report scores for the total score (rs = 0.71) and subscales (rs= 0.69-0.72). Convergent validity was found for both self and informant versions of the RBQ-3, which significantly correlated with DISCO-Abbreviated RRB domain scores (rs = 0.45-0.54). Moreover, the RBQ-3 scores showed significantly weaker association with DISCO -Abbreviated scores for the Social Communication domain, demonstrating divergent validity. Importantly, these patterns of validity were found even when clinicians were blind to RBQ-3 items. In Study 2, for both autistic and non-autistic groups, internal consistency was found for the total score (α = 0.82-0.89, ω = 0.81-0.81) and for subscales (α = 0.68-0.85, ω = 0.69-0.85). A group difference was found between groups.

LIMITATIONS

Due to the characteristics and scope of the specialist autism diagnostic service, further testing is needed to include representative samples of age (including children) and intellectual ability, and those with a non-autistic diagnostic outcome.

CONCLUSIONS

The RBQ-3 is a questionnaire of RRBs that can be used across the lifespan. The current study tested its psychometric properties with autistic adults without intellectual disability and supported its utility for both clinical diagnostic and research settings.

European Autism GEnomics Registry (EAGER): protocol for a multicentre cohort study and registry

INTRODUCTION

Autism is a common neurodevelopmental condition with a complex genetic aetiology that includes contributions from monogenic and polygenic factors. Many autistic people have unmet healthcare needs that could be served by genomics-informed research and clinical trials. The primary aim of the European Autism GEnomics Registry (EAGER) is to establish a registry of participants with a diagnosis of autism or an associated rare genetic condition who have undergone whole-genome sequencing. The registry can facilitate recruitment for future clinical trials and research studies, based on genetic, clinical and phenotypic profiles, as well as participant preferences. The secondary aim of EAGER is to investigate the association between mental and physical health characteristics and participants' genetic profiles.

METHODS AND ANALYSIS

EAGER is a European multisite cohort study and registry and is part of the AIMS-2-TRIALS consortium. EAGER was developed with input from the AIMS-2-TRIALS Autism Representatives and representatives from the rare genetic conditions community. 1500 participants with a diagnosis of autism or an associated rare genetic condition will be recruited at 13 sites across 8 countries. Participants will be given a blood or saliva sample for whole-genome sequencing and answer a series of online questionnaires. Participants may also consent to the study to access pre-existing clinical data. Participants will be added to the EAGER registry and data will be shared externally through established AIMS-2-TRIALS mechanisms.

ETHICS AND DISSEMINATION

To date, EAGER has received full ethical approval for 11 out of the 13 sites in the UK (REC 23/SC/0022), Germany (S-375/2023), Portugal (CE-085/2023), Spain (HCB/2023/0038, PIC-164-22), Sweden (Dnr 2023-06737-01), Ireland (230907) and Italy (CET_62/2023, CEL-IRCCS OASI/24-01-2024/EM01, EM 2024-13/1032 EAGER). Findings will be disseminated via scientific publications and conferences but also beyond to participants and the wider community (eg, the AIMS-2-TRIALS website, stakeholder meetings, newsletters).

Reliability of the Commonly Used and Newly-Developed Autism Measures

PURPOSE

The aim of the present study was to compare scale and conditional reliability derived from item response theory analyses among the most commonly used, as well as several newly developed, observation, interview, and parent-report autism instruments.

METHODS

When available, data sets were combined to facilitate large sample evaluation. Scale reliability (internal consistency, average corrected item-total correlations, and model reliability) and conditional reliability estimates were computed for total scores and for measure subscales.

RESULTS

Generally good to excellent scale reliability was observed for total scores for all measures, scale reliability was weaker for RRB subscales of the ADOS and ADI-R, reflecting the relatively small number of items for these measures. For diagnostic measures, conditional reliability tended to be very good (> 0.80) in the regions of the latent trait where ASD and non-ASD developmental disability cases would be differentiated. For parent-report scales, conditional reliability of total scores tended to be excellent (> 0.90) across very wide ranges of autism symptom levels, with a few notable exceptions.

CONCLUSIONS

These findings support the use of all of the clinical observation, interview, and parent-report autism symptom measures examined, but also suggest specific limitations that warrant consideration when choosing measures for specific clinical or research applications.

Development of Restricted and Repetitive Behaviors from 2-19: Stability and Change in Repetitive Sensorimotor, Insistence on Sameness, and Verbal Behaviors in a Longitudinal Study of Autism

This study examined trajectories of repetitive sensorimotor (RSM), insistence on sameness (IS), and verbal RRBs from ages 2-19 in a well-characterized longitudinal cohort. We also tested the factor structure of the ADI-R restricted and repetitive behavior (RRB) domain at age 19 and the inclusion of a verbal RRBs factor, in addition to previously identified RSM and IS factors, at ages 9 and 19. The ADI-R was administered to 193 participants at five timepoints from 2 to 19. Confirmatory factor analysis (CFA) was used to examine the factor structure of ADI-R RRB data. Change in RRB subtypes was examined using group-based trajectory modeling and multilevel modeling. RSM and IS behaviors generally decreased from 2 to 19, with some participants experiencing increases from ages 2-9. 46.46% of participants experienced increasing verbal RRBs from 2 to 9, followed by a plateau from 9 to 19. The remaining participants had few to no verbal RRBs throughout development. Multilevel modeling indicated ADOS CSS scores were associated with change in RSM trajectories only. Child IQ was not associated with change in any RRB trajectories. CFA indicated previously-derived RSM and IS factors fit age 19 ADI-R data well. The inclusion of a third factor, verbal RRBs, worsened goodness-of-fit statistics and was ultimately omitted. Our findings suggest the RRB factor structure of the ADI remains consistent into early adulthood and illustrate developmental continuity and change in RRBs. For autistic individuals with fluent speech, RRB presentation may be influenced by verbal ability in ways that are highly variable, but clinically meaningful.

Qualitative Exploration Toward the Development of a Parent-Rated Scale for Insomnia in Children with Autism Spectrum Disorder

Toward the development of a new parent-rating for insomnia, this multi-site qualitative study explored sleep problems and related impacts in children with autism spectrum disorder (ASD) and their families. To ensure content validity of the measure, we conducted six focus groups with caregivers (N = 25) of 24 children (age 3 to 18 years) with ASD. Based on parent report, all children had a history of mild or greater insomnia. The focus group transcripts were systematically coded to identify major themes. Verbatim comments from caretakers were used to generate 134 candidate items. Further review by the research team and an expert panel followed by individual cognitive interviews with 12 parents reduced the item bank to 40. The thematic analysis of focus group transcripts identified 7 categories: (1) Trouble falling asleep; (2) trouble staying asleep; (3) early morning waking; (4) bedtime routines; (5) parental strategies for bedtime management; (6) impact of sleep problems on the child; and (7) impact of sleep problems on the family. The Flesch Kincaid Grade Level of the 40-item version was 7.2 (seventh grade reading level). Insomnia in children with ASD shares features in common with insomnia in the general pediatric population. However, perhaps owing to autistic features such as insistence on sameness, sensory sensitivities, communication impairments, insomnia in children with ASD appears to have unique behavioral manifestations. Content validity and item clarity of the 40-item bank were supported by expert panel review and cognitive interviews with caregivers of children with ASD.

Early Behavioral Markers of Anxiety and Reduced Frontal Brain Alpha May Predict High Risk for Bullying Victimization

Bullying victimization has a profound negative impact on a child's emotional, social, and cognitive development. Childhood bullying victimization is reported across various social settings, suggesting common characteristics that increase a child's vulnerability to victimization. It is critical to identify early markers of such vulnerability to design preventative tools. Comprehensive semi-structured clinical interviews from mothers of child-victims and non-engaged control children included assessment of early developmental rituals and behavioral inhibition to social novelty, as potential behavioral correlates of anxiety. Neuropsychological and clinical assessment tools were used, and resting state spectral resting state EEG (rsEEG) was recorded. Increased frequency/severity of early developmental rituals and behaviorally inhibited responses to social novelty were apparent in all child-victims, alongside significantly reduced power of ventral prefrontal brain rsEEG alpha oscillations (8-13 Hz). This triad of findings, in line with prior studies, suggested an elevated early childhood anxiety, which, as current findings indicate, may be a cross-diagnostic marker of increased risk for life-long bullying victimization. Gaining insight into early childhood markers of anxiety may meaningfully complement neuropsychiatric prognosis and preventative efforts.

Characterizing subdomains of insistence on sameness in autistic youth

Insistence on sameness (IS) encompasses a range of behavioral patterns, including resistance to change, routines, and ritualized behaviors, that can be present across social and non-social contexts. Given the breadth of behaviors encompassed by IS, it is important to determine whether this domain is best conceptualized and measured as uni- or a multi-dimensional construct. Therefore, the current study aimed to characterize the structure of IS and explore potentially distinct of patterns of associations between identified IS factors and relevant correlates, including age, sex, IQ, anxiety, social abilities, emotional and behavioral dysregulation, and sensory hypersensitivity. Exploratory graph analysis was conducted using the dimensional assessment of restricted and repetitive behaviors to examine the structure of IS in a sample 1892 autistic youth (Mage  = 10.82, SDage  = 4.14; range: 3-18 years; 420 females) recruited from the Simons Foundation Powering Autism Research for Knowledge cohort. Three distinct IS subdomains labeled as IS-Ritualistic/sameness, IS-Routines, and IS-Others (referring to IS behaviors during interactions with others) were identified. Generalized additive models demonstrated that each of the IS subdomains showed a unique pattern of association with key variables. More specifically, while sensory hypersensitivity was significantly associated with IS-Ritualistic/sameness and IS-Routines, it was not associated with IS-Others. Further, while emotional dysregulation was a unique predictor of IS-Ritualistic/sameness (but not IS-Routines or IS-Others), social interaction abilities were a unique predictor of IS-Routines (but not IS-Ritualistic/sameness or IS-Others). Current findings provide preliminary evidence that the IS may encompass several distinct subdomains.

Exploring the multidimensional nature of repetitive and restricted behaviors and interests (RRBI) in autism: neuroanatomical correlates and clinical implications

BACKGROUND

Repetitive and restricted behaviors and interests (RRBI) are core symptoms of autism with a complex entity and are commonly categorized into 'motor-driven' and 'cognitively driven'. RRBI symptomatology depends on the individual's clinical environment limiting the understanding of RRBI physiology, particularly their associated neuroanatomical structures. The complex RRBI heterogeneity needs to explore the whole RRBI spectrum by integrating the clinical context [autistic individuals, their relatives and typical developing (TD) individuals]. We hypothesized that different RRBI dimensions would emerge by exploring the whole spectrum of RRBI and that these dimensions are associated with neuroanatomical signatures-involving cortical and subcortical areas.

METHOD

A sample of 792 individuals composed of 267 autistic subjects, their 370 first-degree relatives and 155 TD individuals was enrolled in the study. We assessed the whole patterns of RRBI in each individual by using the Repetitive Behavior Scale-Revised and the Yale-Brown Obsessive Compulsive Scale. We estimated brain volumes using MRI scanner for a subsample of the subjects (n = 152, 42 ASD, 89 relatives and 13 TD). We first investigated the dimensionality of RRBI by performing a principal component analysis on all items of these scales and included all the sampling population. We then explored the relationship between RRBI-derived factors with brain volumes using linear regression models.

RESULTS

We identified 3 main factors (with 30.3% of the RRBI cumulative variance): Factor 1 (FA1, 12.7%) reflected mainly the 'motor-driven' RRBI symptoms; Factor 2 and 3 (respectively, 8.8% and 7.9%) gathered mainly Y-BOCS related items and represented the 'cognitively driven' RRBI symptoms. These three factors were significantly associated with the right/left putamen volumes but with opposite effects: FA1 was negatively associated with an increased volume of the right/left putamen conversely to FA2 and FA3 (all uncorrected p < 0.05). FA1 was negatively associated with the left amygdala (uncorrected p < 0.05), and FA2 was positively associated with the left parietal structure (uncorrected p = 0.001).

CONCLUSION

Our results suggested 3 coherent RRBI dimensions involving the putamen commonly and other structures according to the RRBI dimension. The exploration of the putamen's integrative role in RSBI needs to be strengthened in further studies.

Febrile Seizure Causes Deficit in Social Novelty, Gliosis, and Proinflammatory Cytokine Response in the Hippocampal CA2 Region in Rats

Febrile seizure (FS), which occurs as a response to fever, is the most common seizure that occurs in infants and young children. FS is usually accompanied by diverse neuropsychiatric symptoms, including impaired social behaviors; however, research on neuropsychiatric disorders and hippocampal inflammatory changes following febrile seizure occurrences is very limited. Here, we provide evidence linking FS occurrence with ASD pathogenesis in rats. We developed an FS juvenile rats model and found ASD-like abnormal behaviors including deficits in social novelty, repetitive behaviors, and hyperlocomotion. In addition, FS model juvenile rats showed enhanced levels of gliosis and inflammation in the hippocampal CA2 region and cerebellum. Furthermore, abnormal levels of social and repetitive behaviors persisted in adults FS model rats. These findings suggest that the inflammatory response triggered by febrile seizures in young children could potentially serve as a mediator of social cognitive impairments.

Molehill Mountain feasibility study: Protocol for a non-randomised pilot trial of a novel app-based anxiety intervention for autistic people

Up to 50% of autistic people experience co-occurring anxiety, which significantly impacts their quality of life. Consequently, developing new interventions (and/ or adapting existing ones) that improve anxiety has been indicated as a priority for clinical research and practice by the autistic community. Despite this, there are very few effective, evidence-based therapies available to autistic people that target anxiety; and those that are available (e.g., autism adapted Cognitive Behavioural Therapy; CBT) can be challenging to access. Thus, the current study will provide an early-stage proof of concept for the feasibility and acceptability of a novel app-based therapeutic approach that has been developed with, and adapted for, autistic people to support them in managing anxiety using UK National Institute for Health and Care Excellence (NICE) recommended adapted CBT approaches. This paper describes the design and methodology of an ethically approved (22/LO/0291) ongoing non-randomised pilot trial that aims to enrol approximately 100 participants aged ≥16-years with an existing autism diagnosis and mild-to-severe self-reported anxiety symptoms (trial registration NCT05302167). Participants will be invited to engage with a self-guided app-based intervention-'Molehill Mountain'. Primary (Generalised Anxiety Disorder Assessment, Hospital Anxiety and Depression Scale) and secondary outcomes (medication/ service use and Goal Attainment Scaling) will be assessed at baseline (Week 2 +/- 2), endpoint (Week 15 +/- 2) and three follow-ups (Weeks 24, 32 and 41 +/- 4). Participants will also be invited to complete an app acceptability survey/ interview at the study endpoint. Analyses will address: 1) app acceptability/ useability and feasibility (via survey/ interview and app usage data); and 2) target population, performance of outcome measures and ideal timing/ duration of intervention (via primary/ secondary outcome measures and survey/ interview)-with both objectives further informed by a dedicated stakeholder advisory group. The evidence from this study will inform the future optimisation and implementation of Molehill Mountain in a randomised-controlled trial, to provide a novel tool that can be accessed easily by autistic adults and may improve mental health outcomes.

Arriving at the empirically based conceptualization of restricted and repetitive behaviors: A systematic review and meta-analytic examination of factor analyses

An empirically based understanding of the factor structure of the restricted and repetitive behaviors (RRB) domain is a prerequisite for interpreting studies attempting to understand the correlates and mechanisms underpinning RRB and for measurement development. Therefore, this study aimed to conduct a systematic review and meta-analysis of RRB factor analytic studies. Sets of meta-analyses were performed to examine (a) the factor structure of individual RRB instruments, (b) associations between RRB subdomains across instruments, and (c) the association between RRB factors and other variables. Searches for peer-reviewed articles evaluating the factor structure of the RRB domain were performed in PsycINFO (Ovid), Medline (Ovid), and Embase (Ovid). No age, measurement, or informant-type limits were imposed. Quality and risk of bias for individual studies were assessed using relevant COSMIN sections. Among the 53 studies retained for review, 41 examined RRB factor structures among individuals with autism spectrum disorder (ASD) and 12 among non-ASD samples. Meta-analysis of factor correlations provided evidence that the RRB domain encompasses the following eight specific factors: repetitive motor behaviors, insistence on sameness, restricted interests, unusual interests, sensory sensitivity, and repetitive, stereotyped language. Although interrelated, RRB factors were distinct, showing a unique pattern of associations with demographic, cognitive, and clinical correlates. Meta-analyses of the associations between RRB factors and specific correlates, specifically adaptive functioning and communication impairments, should be considered preliminary due to the limited number of studies. Despite limitations, this review provides important insights into the factor structure of the RRB domain and highlights critical conceptual, measurement, and methodological limitations of the current research that will need to be addressed in order to improve our understanding of RRB.

Predicting intervention use in autistic children: Demographic and autism-specific characteristics

LAY ABSTRACT

Autism is a condition that is characterised by social communication difficulties and restrictive and repetitive behaviours or interests. Autism can present in many different ways and various interventions are available. Some interventions are conventional, and they are recommended to be used for children with autism (guideline therapies) or for other disorders such as anxiety or attention-deficit hyperactivity disorder (mainstream therapies or medication), while others are less conventional (other therapies or medication, they are discouraged, unknown or alternative). Little is known about who chooses which intervention. This study found that most autistic children use some kind of intervention. Children who attend special education or have an additional diagnosis (other than autism) tend to receive more therapies, while children with a lower IQ receive fewer therapies. Older children, children with a higher IQ and girls are more likely to use conventional (mainstream or guideline) therapies. Children whose parents have a lower educational level are more likely to have used conventional medication. Whereas, children with more sensory issues (e.g. sensitivity to sound, smell or movement) were more likely to have used unconventional medication. This study found that other autism-related characteristics such as the number of autism symptoms, social skills and repetitive and restrictive behaviours were not related to the interventions used. More treatments focussed on multiple problems should be available for children with autism who have additional difficulties.

Restricted and repetitive behaviors and their developmental and demographic correlates in 4-8-year-old children: A transdiagnostic approach

Background: Restricted and repetitive behaviors (RRBs) are a broad class of behaviors characterized by frequent action repetition and intense preference for sameness. Research has predominantly focused on RRBs in diagnosed clinical groups, particularly in autism spectrum disorder and genetic disorders. Using a transdiagnostic approach, the current study examined RRBs in a diverse sample of children in relation to developmental and demographic correlates (age, language, non-verbal ability, child anxiety, sex, and socioeconomic status). Separate analyses examined two RRB subtypes; repetitive sensory and motor behaviors (RSMB) and insistence on sameness (IS). Method: Children (N = 260, age 4-8 years, 174 male, 86 female) in mainstream schools identified by teachers as having behavioral, emotional, and/or cognitive difficulties, were assessed using the Repetitive Behavior Questionnaire-2 (RBQ-2), the British Picture Vocabulary Scale (BPVS), Lucid Ability Scale, the Welsh Index of Multiple Deprivation (WIMD) and the Screen for Child Anxiety Related Emotional Disorders (SCARED). Recruitment excluded diagnosed clinical conditions. The Strengths and Difficulties Questionnaire (SDQ) was used to assess children's difficulties. Results: RRB scores were of high frequency and the scores for the IS were higher than for RSMB. The severity of anxiety symptoms and male sex were significantly associated with both RRB subtypes, and younger age and SES scores were associated with IS. Elevated RRB total and subtype scores were significantly related to SDQ scores for emotion, conduct, hyperactivity, and peer-relations. Discussion: The study provides the first evidence of RRBs in a diverse sample of young children with emerging difficulties in behavior, cognition, and/or emotion. The results contribute to proposals about psychological development in RRB and indicate that RRBs are best represented on a continuum of severity found across children in the early school years. The results support previous findings of a relation between RRB and anxiety reported in clinical samples and importantly, they indicate that it is time to move beyond the study of categorically defined groups and consider correlates of RRBs that include broad indices of mental health and well-being.

Dimensional Assessment of Restricted and Repetitive Behaviors: Development and Preliminary Validation of a New Measure

OBJECTIVE

This study aimed to provide initial validation of the Dimensional Assessment of Restricted and Repetitive Behaviors (DARB), a new parent-report measure designed to capture the full range of key restricted and repetitive behaviors (RRB) subdomains.

METHOD

Parents of 1,892 children and adolescents with autism spectrum disorder (mean [SD] age = 10.81 [4.14] years) recruited from the SPARK (Simons Foundation Powering Autism Research for Knowledge) research match completed the DARB, several existing RRB instruments, and measures of social and communication impairments and anxiety. A subsample of 450 parents completed the DARB after 2 weeks to evaluate the test-retest stability.

RESULTS

Exploratory graph analysis conducted in the exploratory subsample identified 8 dimensions that were aligned with hypothesized RRB subdomains: repetitive sensory motor behaviors, insistence on sameness, restricted interests, unusual interests, sensory sensitivity, self-injurious behaviors, obsessions and compulsive behaviors, and repetitive language. The confirmatory application of the exploratory structural equation modeling conducted in the confirmatory subsample showed that the derived factor structure had a good fit to the data. Derived factors had excellent reliability, convergent and divergent validity, and very strong test-retest stability and showed a distinct pattern of associations with key demographic, cognitive and clinical correlates.

CONCLUSION

The DARB will be useful in a variety of research and clinical contexts considering the prominence and clinical impact of RRB in autism spectrum disorder. Strong preliminary evidence indicates that the new scale is comprehensive and captures a wide range of distinct RRB subdomains not simultaneously captured by any of the existing instruments.

Brief report: Validity and reliability of the Nigerian Autism Screening Questionnaire

Informant-report measures for screening symptoms of autism spectrum disorder (ASD) and other neurodevelopmental disorders (NDDs) are needed for low-resource settings if early identification is to be prioritized because early developmental concerns are likely to be expressed by parents and other caregivers. This paper describes the initial psychometric evaluation of the Nigeria Autism Screening Questionnaire (NASQ). Parents and other caregivers completed the NASQ on 12,311 children ages 1 to 18 in a Nigerian population sample as part of the World Bank National General Household Survey conducted in the country in 2016. Factor analyses indicated a parsimonious three-factor structure with social communication/interaction, repetitive sensory motor, and insistence on sameness dimensions. Measurement invariance was excellent across age and sex. Reliability of the subscales and total scale was good, and item response theory analyses indicated good measurement precision in the range from below average to high scores, crucial for screening, and tracking ASD symptoms. Studies with gold standard ASD diagnostic instruments and clinical confirmation are needed to evaluate screening and diagnostic accuracy. The NASQ appears to be a reliable instrument with a clear factor structure and potential for use in screening and tracking ASD symptoms in future Nigerian samples.

Repetitive Restricted Behaviors in Autism Spectrum Disorder: From Mechanism to Development of Therapeutics

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by deficits in social communication, social interaction, and repetitive restricted behaviors (RRBs). It is usually detected in early childhood. RRBs are behavioral patterns characterized by repetition, inflexibility, invariance, inappropriateness, and frequent lack of obvious function or specific purpose. To date, the classification of RRBs is contentious. Understanding the potential mechanisms of RRBs in children with ASD, such as neural connectivity disorders and abnormal immune functions, will contribute to finding new therapeutic targets. Although behavioral intervention remains the most effective and safe strategy for RRBs treatment, some promising drugs and new treatment options (e.g., supplementary and cell therapy) have shown positive effects on RRBs in recent studies. In this review, we summarize the latest advances of RRBs from mechanistic to therapeutic approaches and propose potential future directions in research on RRBs.

Big Data Approach to Characterize Restricted and Repetitive Behaviors in Autism

OBJECTIVE

Despite being a core diagnostic feature of autism spectrum disorder (ASD), demographic, developmental and clinical correlates of restricted and repetitive behaviors and interests (RRB) remain poorly characterized. This study aimed to utilize the largest available RRB data set to date to provide a comprehensive characterization of how distinct RRB domains vary according to a range of individual characteristics.

METHOD

Data were obtained from 17,581 children and adolescents with ASD (mean_age= 8.24 years, SD_age= 4.06) from the Simons Foundation Powering Autism Research for Knowledge cohort. Caregivers completed the Repetitive Behavior Scale-Revised questionnaire as a measure of repetitive motor behaviors, self-injurious behaviors, compulsions, insistence on sameness, and circumscribed interests RRB domains. Caregivers also provided information on children's cognitive functioning, language ability, and social and communication impairments.

RESULTS

Male sex was associated with higher severity of repetitive motor behaviors and restricted interests and with lower severity of compulsions and self-injurious behaviors; no sex differences were found for the insistence on sameness domain. Although repetitive motor behaviors showed a mostly linear (negative) association with age, other RRB domains showed more complex and nonlinear pattern of associations. Higher severity of social and communication impairments provided significant independent contribution in predicting higher severity of all RRB domains at the p < .001 level; however, these effects were small (d < 0.25). The strongest of these effects was observed for insistence on sameness (d = 0.24), followed by repetitive motor behaviors (d = 0.21), compulsions (d = 0.17), restricted interests (d = 0.14), and self-injurious behaviors (d = 0.12).

CONCLUSION

Findings reported here provide further evidence that RRB subdomains show a somewhat distinct pattern of associations with demographic, developmental, and clinical variables, with a key implication that separate consideration of these domains can help to facilitate efforts to understand diverse ASD etiology and to inform the design of effective interventions.

The Monash Autism-ADHD genetics and neurodevelopment (MAGNET) project design and methodologies: a dimensional approach to understanding neurobiological and genetic aetiology

Background

ASD and ADHD are prevalent neurodevelopmental disorders that frequently co-occur and have strong evidence for a degree of shared genetic aetiology. Behavioural and neurocognitive heterogeneity in ASD and ADHD has hampered attempts to map the underlying genetics and neurobiology, predict intervention response, and improve diagnostic accuracy. Moving away from categorical conceptualisations of psychopathology to a dimensional approach is anticipated to facilitate discovery of data-driven clusters and enhance our understanding of the neurobiological and genetic aetiology of these conditions. The Monash Autism-ADHD genetics and neurodevelopment (MAGNET) project is one of the first large-scale, family-based studies to take a truly transdiagnostic approach to ASD and ADHD. Using a comprehensive phenotyping protocol capturing dimensional traits central to ASD and ADHD, the MAGNET project aims to identify data-driven clusters across ADHD-ASD spectra using deep phenotyping of symptoms and behaviours; investigate the degree of familiality for different dimensional ASD-ADHD phenotypes and clusters; and map the neurocognitive, brain imaging, and genetic correlates of these data-driven symptom-based clusters.

Methods

The MAGNET project will recruit 1,200 families with children who are either typically developing, or who display elevated ASD, ADHD, or ASD-ADHD traits, in addition to affected and unaffected biological siblings of probands, and parents. All children will be comprehensively phenotyped for behavioural symptoms, comorbidities, neurocognitive and neuroimaging traits and genetics.

Conclusion

The MAGNET project will be the first large-scale family study to take a transdiagnostic approach to ASD-ADHD, utilising deep phenotyping across behavioural, neurocognitive, brain imaging and genetic measures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00457-3.

Discriminant value of repetitive behaviors in families with autism spectrum disorder and obsessional compulsive disorder probands

Repetitive behaviors (RB) represent a wide spectrum of symptoms ranging from sensory-motor stereotypies to complex cognitive rituals, frequently dichotomized as low- and high-order sub-groups of symptoms. Even though these subgroups are considered as phenomenologically distinct in autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD), brain imaging and genetic studies suggest that they have common mechanisms and pathways. This discrepancy may be explained by the frequent intellectual disability reported in ASD, which blurs the RB expressivity. Given the high heritability of RB, that is, the diversity of symptoms expressed in the relatives are dependent on those expressed in their probands, we hypothesize that if RB expressed in ASD or OCD are two distinct entities, then the RB expressed in relatives will also reflect these two dimensions. We thus conduct a linear discriminant analysis on RB in both the relatives of probands with ASD and OCD and subjects from the general population (n = 1023). The discriminant analysis results in a classification of 81.1% of the controls (p < 10^-4 ), but poorly differentiated the ASD and OCD relatives (≈46%). The stepwise analysis reveals that five symptoms attributed to high-order RB and two related to low-order RB (including hypersensitivity) are the most discriminant. Our results support the idea that the difference of RB patterns in the relatives is mild compared with the distribution of symptoms in controls. Our findings reinforce the evidence of a common biological pattern of RB both in ASD and OCD but with minor differences, specific to each of these two neuro-developmental disorders. LAY SUMMARY: Repetitive behaviors (RB), a key symptom in the classification of both OCD and ASD, are phenomenologically considered as distinct in the two disorders, which is in contrast with brain imaging studies describing a common neural circuit. Intellectual disability, which is frequently associated with ASD, makes RB in ASD more difficult to understand as it affects the expression of the RB symptoms. To avoid this bias, we propose to consider the familial aggregation in ASD and OCD by exploring RB in the first-degree relatives of ASD and OCD. Our results highlight the existence of RB expressed in relatives compared to the general population, with a common pattern of symptoms in relatives of both ASD and OCD but also minor differences, specific to each of these two neuro-developmental disorders.

Using the big data approach to clarify the structure of restricted and repetitive behaviors across the most commonly used autism spectrum disorder measures

BACKGROUND

Restricted and repetitive behaviors (RRB) in autism spectrum disorder (ASD) encompass several distinct domains. However, commonly used general ASD measures provide broad RRB scores rather than assessing separate RRB domains. The main objective of the current investigation was to conduct a psychometric evaluation of the ability of the Social Responsiveness Scale (SRS-2), the Social Communication Questionnaire (SCQ), the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) to capture different RRB constructs.

METHODS

Exploratory Structural Equation Modeling (ESEM) was conducted using individual item-level data from the SRS-2, SCQ, ADI-R and the ADOS. Data were obtained from five existing publicly available databases. For the SRS-2, the final sample consisted of N = 16,761 individuals (Mage = 9.43, SD = 3.73; 18.5% female); for the SCQ, of N = 15,840 (Mage = 7.99, SD = 4.06; 18.1% female); for the ADI-R, of N = 8985 (Mage = 8.86, SD = 4.68; 19.4% female); and for the ADOS, of N = 6314 (Mage = 12.29, SD = 6.79; 17.7% female).

RESULTS

The three-factor structure provided the most optimal and interpretable fit to data for all measures (comparative fit index ≥ .983, Tucker Lewis index ≥ .966, root mean square error of approximation ≤ .028). Repetitive-motor behaviors, insistence on sameness and unusual or circumscribed interests factors emerged across all instruments. No acceptable fit was identified for the ADOS.

LIMITATIONS

The five datasets used here afforded a large as well as wide distribution of the RRB item scores. However, measures used for establishing convergent and divergent validity were only available for a portion of the sample.

CONCLUSIONS

Reported findings offer promise for capturing important RRB domains using general ASD measures and highlight the need for measurement development.

The science of humanity and the humanity of science: Perspectives on Ed Zigler's contributions to developmental psychopathology and the study of all children

We present this article as a testament to Ed Zigler's commitment to science in the service of humanity and to policy based on conceptually compelling theory and methodologically rigorous science. In doing so, we highlight ways that Ed's universal and inclusive developmental world view, early training as a behaviorist, exacting scientific standards, concern for others, and appreciation of his own roots and upbringing all transformed the way that many different groups of people of all ages and backgrounds are studied, viewed, and intervened with by researchers, policy makers, and society at large. Ed's narrative of development rather than defect, universality rather than difference, and holistic rather than reductionist continues to compel us in the quest for a kinder, more inclusive, and enabling society. Conversely, Ed's behaviorist training as a graduate student also influenced him throughout his career and was essential to his career-long commitment to systemic action in the service of improving the lives of others. We cite the lessons that we, as his descendants, learned from Ed and apply them to our own areas of research with populations that Ed did not study, but had considerable interest in - persons with autism spectrum disorder and Indigenous youth.

Evaluating the latent structure of the non-social domain of autism in autistic adults

Background

The social domain of autism has been studied in depth, but the relationship between the non-social traits of autism has received less attention. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) outlines four criteria that make up the non-social domain including repetitive motor movements, insistence on sameness, restricted interests and sensory sensitivity. There is a lack of research into the relationship between these four criteria. This study aimed to evaluate the relationship between the non-social traits of autism in a large sample of autistic adults. It explored whether these traits are best conceptualised as four distinct factors, or exist along a single dimension.

Methods

Participants included autistic adults from the Netherlands Autism Register. The four components identified within the DSM-5 non-social domain were measured by items from the Adult Routines Inventory, the Autism Spectrum Quotient short and the Sensory Perception Quotient short. Confirmatory factor analysis, as well as exploratory factor analysis and exploratory structural equation modelling, was implemented to examine the relationship between these four criteria.

Results

Results indicated that a four-factor model provided the best fit, mapping onto the DSM-5 criteria. These four factors were moderately correlated, suggesting that four distinct, yet related factors best describe the non-social domain of autism. The one-factor model did not provide a good fit, highlighting that the non-social domain of autism is not a unitary construct.

Limitations

The study included autistic adults who were cognitively able to complete the self-report measures. This may limit the generalisability of the findings to those who are less able to do so.

Conclusions

This study provided evidence for the multidimensional nature of the non-social domain of autism. Given only two of the four criteria within the non-social domain need to be endorsed for a diagnosis of autism, there is room for substantial variation across individuals, who will have a unique profile within the non-social domain. The results have implications for our understanding of the heterogeneous nature of autistic traits, as well as for how we conceptualise autism as a diagnostic category. This is important for the provision of diagnosis and support within research and clinical practice.

Brief Report: Role of Parent-Reported Executive Functioning and Anxiety in Insistence on Sameness in Individuals with Germline PTEN Mutations

This study aimed to characterize the relationship between insistence on sameness (IS), executive functioning (EF) and anxiety among individuals with PTEN mutations and individuals with macrocephalic ASD. The sample included 38 individuals with PTEN mutation and ASD diagnosis (PTEN-ASD; M_age = 8.93 years, SD_age = 4.75), 23 with PTEN mutation without ASD (PTEN-no ASD; M_age = 8.94 years; SD_age = 4.85) and 25 with ASD and macrocephaly but with no PTEN mutation (Macro-ASD; M_age = 11.99 years; SD_age = 5.15). The final model accounted for 45.7% of variance in IS, with Set-Shifting EF subdomain as a unique independent predictor (t = 4.12, p < 0.001). This investigation provides the first preliminary evidence for the EF-anxiety-IS interrelationship in individuals with PTEN mutations and with macrocephalic ASD.

The Multi-Targeting Ligand ST-2223 with Histamine H3 Receptor and Dopamine D2/D3 Receptor Antagonist Properties Mitigates Autism-Like Repetitive Behaviors and Brain Oxidative Stress in Mice

Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characterized by social and communicative impairments, as well as repetitive and restricted behaviors (RRBs). With the limited effectiveness of current pharmacotherapies in treating repetitive behaviors, the present study determined the effects of acute systemic treatment of the novel multi-targeting ligand ST-2223, with incorporated histamine H₃ receptor (H₃R) and dopamine D₂/D₃ receptor affinity properties, on ASD-related RRBs in a male Black and Tan BRachyury (BTBR) mouse model of ASD. ST-2223 (2.5, 5, and 10 mg/kg, i.p.) significantly mitigated the increase in marble burying and self-grooming, and improved reduced spontaneous alternation in BTBR mice (all p < 0.05). Similarly, reference drugs memantine (MEM, 5 mg/kg, i.p.) and aripiprazole (ARP, 1 mg/kg, i.p.), reversed abnormally high levels of several RRBs in BTBR (p < 0.05). Moreover, ST-2223 palliated the disturbed anxiety levels observed in an open field test (all p < 0.05), but did not restore the hyperactivity parameters, whereas MEM failed to restore mouse anxiety and hyperactivity. In addition, ST-2223 (5 mg/kg, i.p.) mitigated oxidative stress status by decreasing the elevated levels of malondialdehyde (MDA), and increasing the levels of decreased glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in different brain parts of treated BTBR mice (all p < 0.05). These preliminary in vivo findings demonstrate the ameliorative effects of ST-2223 on RRBs in a mouse model of ASD, suggesting its pharmacological prospective to rescue core ASD-related behaviors. Further confirmatory investigations on its effects on various brain neurotransmitters, e.g., dopamine and histamine, in different brain regions are still warranted to corroborate and expand these initial data.

Developmental Perspectives on the Study of Persons with Intellectual Disability

Developmental approaches provide inclusive, universal, and methodologically rigorous frameworks for studying persons with intellectual disability (ID). This is an exceptionally heterogeneous group with regard to etiology, genotype, and phenotype that simply shares the traditional diagnostic criteria, typically a score of two standard deviations below the population mean of 100 on standardized IQ tests and deficits in adaptive behavior. We trace the foundational, conceptual, and methodological roots of developmental approaches and highlight ways that these and more recent iterations continue to be central to advances in the increasingly nuanced study of persons with ID. This work is premised on the consideration of specific etiological groupings and subgroupings across and between different domains of functioning within the context of familial and complex environments throughout the life span. We highlight the potential contributions of advances in behavioral methodologies, genomics, and neuroscience when considered within universal and hierarchic frameworks based on development.

Domains of the autism phenotype, cognitive control, and rumination as transdiagnostic predictors of DSM-5 suicide risk

Suicide is a global health problem affecting both normative and clinical populations. Theoretical models that examine mechanisms underlying suicide risk across heterogeneous samples are needed. The present study explored core characteristics associated with autism spectrum disorder (ASD), a sub-population at high risk of suicide, as well as two dimensional cognitive constructs, as potential transdiagnostic predictors of suicidal ideation in a clinically diverse sample. Participants (n = 1851, 62% female) aged 18 to 89 years completed online questionnaires assessing: social communication difficulties; insistence on sameness; cognitive control; and rumination. Forty-three percent of participants reported the presence of at least one neurodevelopmental or neuropsychiatric disorder. One third of the sample reported some suicidal ideation (SI), and 40 percent met the threshold for concern for depression. All hypothesized constructs were associated with SI and depression and, with the exception of rumination, contributed significantly to SI. Participants reporting SI returned significantly higher social communication difficulties and insistence on sameness, and lower levels of cognitive control than those reporting no-SI. The study was limited by the use of a cross-sectional sample assessed with self-report measures. All diagnoses were self-reported and the study was additionally limited by the use of a single item indicator of suicidal ideation. These findings support a role for constructs associated with the ASD phenotype and associated broad cognitive domains as potential risk factors underlying suicidal ideation in a large clinically diverse sample. Our findings suggest directions for future longitudinal research studies, along with specific targets for suicide prevention and clinical practice.

Longitudinal change in restricted and repetitive behaviors from 8-36 months

BACKGROUND

Restricted and repetitive behaviors (RRBs) are core features of autism spectrum disorder (ASD) and one of the earliest behavioral signs of ASD. However, RRBs are also present in typically developing (TD) infants, toddlers, and preschool-aged children. Past work suggests that examining change in these behaviors over time is essential to distinguish between normative manifestations of these behaviors and behaviors that denote risk for a neurodevelopmental disorder. One challenge in examining changes in these behaviors over time is that most measures of RRBs have not established longitudinal measurement invariance. The aims of this study were to (1) establish measurement invariance in the Repetitive Behavior Scales for Early Childhood (RBS-EC), a parent-report questionnaire of RRBs, and (2) model developmental change in RRBs from 8 to 36 months.

METHODS

We collected RBS-EC responses from parents of TD infants (n = 180) from 8 to 36 months (n = 606 responses, with participants contributing an average of 3-time points). We leverage a novel methodological approach to measurement invariance testing (Bauer, Psychological Models, 22(3), 507-526, 2017), moderated nonlinear factor analysis (MNLFA), to determine whether the RBS-EC was invariant across age and sex. We then generated adjusted factor score estimates for each subscale of the RBS-EC (repetitive motor, self-directed, and higher-order behaviors), and used linear mixed effects models to estimate between- and within-person changes in the RBS-EC over time.

RESULTS

The RBS-EC showed some non-invariance as a function of age. We were able to adjust for this non-invariance in order to more accurately model changes in the RBS-EC over time. Repetitive motor and self-directed behaviors showed a linear decline from 8 to 36 months, while higher-order behaviors showed a quadratic trajectory such that they began to decline later in development at around 18 months. Using adjusted factor scores as opposed to unadjusted raw mean scores provided a number of benefits, including increased within-person variability and precision.

CONCLUSIONS

The RBS-EC is sensitive enough to measure the presence of RRBs in a TD sample, as well as their decline with age. Using factor score estimates of each subscale adjusted for non-invariance allowed us to more precisely estimate change in these behaviors over time.

Brief Report: Emotion Regulation Influences on Internalizing and Externalizing Symptoms Across the Normative-Clinical Continuum

Emotion regulation is theorized to be a transdiagnostic process and has been empirically shown to be associated with various mental health and neurodevelopmental conditions. However, the relationship between emotion regulation and internalizing and externalizing symptoms has yet to be characterized in a sample of individuals spanning normative and atypical development. Therefore, this study aimed to provide initial evidence for emotion regulation as a transdiagnostic process of internalizing and externalizing symptoms in a community sample of adolescents with and without neuropsychiatric and neurodevelopmental conditions. The sample consisted of 1,705 caregivers of adolescents aged between 11 and 17 years (M _age = 14.53, SD _age = 1.96). Adolescents were typically developing or had a caregiver-reported diagnosis of autism spectrum disorder, attention-deficit hyperactivity disorder, or anxiety. The typically developing adolescents had significantly better caregiver-reported emotion regulation than adolescents with caregiver-reported neuropsychiatric and neurodevelopmental conditions. Additionally, emotion dysregulation significantly and positively correlated with and predicted internalizing and externalizing symptoms within each subgroup. Importantly, emotion dysregulation had a unique contribution to individual differences in the severity of internalizing and externalizing symptoms, above and beyond the diagnostic status. The research and translational implications of the study findings are discussed.

Examining criterion-oriented validity of the Repetitive Behavior Scales for Early Childhood (RBS-EC) and the Video-Referenced Rating of Reciprocal Social Behavior (vrRSB)

Improved characterization of quantitative traits and dimensionally distributed complex behaviors during toddlerhood may improve early identification of autism spectrum disorder and related neurodevelopmental disorders. Parents of 205 community-ascertained toddlers (age: mean = 20.2, SD = 2.6 months) completed the Repetitive Behavior Scales for Early Childhood (RBS-EC) and the Video-Referenced Rating of Reciprocal Social Behavior (vrRSB), with longitudinal follow-up of behavioral assessments and/or another round of parent-report questionnaires. Criterion validity was examined both concurrently and longitudinally using the Infant Toddler Social Emotional Assessment (ITSEA) as a criterion anchor. Reciprocal social behavior as measured by the vrRSB was significantly associated with social competence as measured by the ITSEA, longitudinally and concurrently. Reciprocal social behavior was not associated with the externalizing subscale on the ITSEA, providing evidence of discriminant validity. Higher-order repetitive behaviors (restricted interests; rituals and routines) as measured by RBS-EC subscales were associated with the dysregulation and internalizing subscales of the ITSEA, longitudinally and concurrently. All RBS-EC subscales (excepting repetitive motor) were associated concurrently and longitudinally with the dysregulation subscale of the ITSEA. We report evidence of criterion-oriented and discriminant validity for the constructs/domains captured by the RBS-EC and vrRSB. These instruments may be particularly useful in characterizing dimensional variability across the typical-to-atypical continuum.

The autism advantage at work: A critical and systematic review of current evidence

BACKGROUND

Despite difficulties entering the workforce, people on the autism spectrum are often successful. Furthermore, they are suggested to bring unique abilities (e.g., attention to detail, tolerance for repetitive tasks) related to the repetitive and restrictive behaviours and interests (RRBI) diagnostic domain, that may be advantageous in employment.

AIMS

This critical and systematic review examined evidence supporting the superior workplace performance of employees on the autism spectrum, particularly regarding the RRBI domain.

METHOD AND PROCEDURES

A systematic review (PRISMA guidelines) evaluated empirical peer-reviewed studies that assess employees on the autism spectrum's performance in the workplace or on work-specific tasks. Nine databases were searched, with additional papers identified from reference lists and consultation.

OUTCOMES AND RESULTS

Two quantitative and four qualitative papers met criteria. Results reflect themes; attention to detail, tolerance of repetitive tasks, special/circumscribed interests, other RRBI related advantages/concerns.

CONCLUSIONS AND IMPLICATIONS

Due to the nature and quality of the identified studies there is currently no strong evidence supporting or negating a workplace autism advantage. This review highlights the need for more research and urges constraint in utilising stereotypes that may not apply to all on the autism spectrum, arguing an individual differences approach to supporting autism strengths at work.

Deconstructing the repetitive behaviour phenotype in autism spectrum disorder through a large population-based analysis

OBJECTIVE

Restricted and repetitive pattern of behaviours and interests (RRB) are a cardinal feature of autism spectrum disorder (ASD), but there remains uncertainty about how these diverse behaviours vary according to individual characteristics. This study provided the largest exploration to date of the relationship between Repetitive Motor Behaviours, Rigidity/Insistence on Sameness and Circumscribed Interests with other individual characteristics in newly diagnosed individuals with ASD.

METHOD

Participants (N = 3,647; 17.7% females; Mage = 6.6 years [SD = 4.7]) were part of the Western Australian (WA) Register for ASD, an independent, prospective collection of demographic and diagnostic data of newly diagnosed cases of ASD in WA. Diagnosticians rated each of the DSM-IV-TR criteria on a 4-point Likert severity scale, and here we focused on the Repetitive Motor Behaviours, Insistence on Sameness and Circumscribed Interests symptoms.

RESULTS

The associations between RRB domains, indexed by Kendall's Tau, were weak, ranging from non-significant for both Circumscribed Interests and Repetitive Motor Behaviours to significant (.20) for Insistence on Sameness and Repetitive Motor Behaviours. Older age at diagnosis was significantly associated with lower Circumscribed Interests and significantly associated with higher Insistence on Sameness and Repetitive Motor Behaviours. Male sex was significantly associated with higher Repetitive Motor Behaviours but not Insistence on Sameness or Circumscribed Interests.

CONCLUSIONS

The pattern of associations identified in this study provides suggestive evidence for the distinctiveness of Repetitive Motor Behaviours, Insistence on Sameness and Circumscribed Interests, highlighting the potential utility of RRB domains for stratifying the larger ASD population into smaller, more phenotypically homogeneous subgroups that can help to facilitate efforts to understand diverse ASD aetiology and inform design of future interventions.

Short report: Social communication difficulties and restricted repetitive behaviors as predictors of anxiety in adults with autism spectrum disorder

Autism spectrum disorder and anxiety are highly comorbid conditions. Understanding the underlying traits of anxiety in autism spectrum disorder is crucial to prevent and treat it efficiently. Hence, this study determined whether social communication difficulties or restricted repetitive behaviors are stronger risk factors for anxiety symptoms in autistic adults in a large cohort. Data on 742 autistic adults from the Netherlands Autism Register were included in the study. Hierarchical regression was implemented to evaluate whether social communication difficulties (Autism-Spectrum Quotient social behavior factor) and restricted repetitive behaviors (Adult Routines Inventory) were predictive of anxiety (Hospital Anxiety and Depression Scale) controlling for age and sex. When considered together, restricted repetitive behaviors stood out as significant positive predictors of anxiety symptoms (lower-order restricted repetitive behaviors, β = 0.32, p < 0.001; higher-order restricted repetitive behaviors, β = 0.15, p = 0.001), whereas social communication difficulties did not (β = 0.06, p = 0.11). Sex did not moderate these associations (p > 0.05). Non-social autistic traits are stronger predictors of anxiety symptoms than social traits in autistic adults. Increased attention to restricted repetitive behaviors should be given to improve current support programs for autistic adults with anxiety and to identify autistic individuals at risk.

Gender differences in restricted and repetitive behaviors and interests in youth with autism

Previous work has found gender differences in restricted and repetitive behaviors and interests (RRBI) for autism spectrum disorder (ASD). Compared to girls, affected boys have increased stereotyped and restricted behaviors; however much less is known about gender differences in other areas of RRBI. This study aims to identify whether specific RRBI (i.e., stereotyped, self-injurious, compulsive, insistence on sameness, ritualistic, and restricted), as measured by item-level data on the Repetitive Behavior Scale-Revised (RBS-R), can distinguish girls from boys with ASD. Participants included 615 individuals with ASD (507 boys; 82.4%), ages 3-18 years of age (M = 10.26, SD = 4.20), who agreed to share data with the National Database for Autism Research (NDAR). Multivariate analysis of variance and discriminant function analysis (DFA) were used to determine whether item-level RBS-R data could correctly classify cases by gender. DFA results suggest that RBS-R items significantly differentiate gender. Strongly differentiating RBS-R items had greater success in correctly classifying affected boys (67.90%) than girls (61.00%). Items that best-discriminated gender were heightened stereotyped behaviors and restricted interests items in boys and compulsive, sameness, restricted, and self-injurious behavior items in girls. This study is the first to find that girls with ASD may have increased compulsive, sameness, and restricted RRBI compared to boys. Additionally, findings support heightened self-injurious behaviors in affected girls. Future research should disentangle whether elevated rates of RRBI in girls are central to the presentation of ASD in girls or an epiphenomenon of the high rates of co-occurring disorders (e.g., anxiety) noted in girls. Autism Res 2019, 12: 274-283 © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: This study is the first to examine a comprehensive measure of repetitive behavior in children with autism, with findings of increased compulsive, insistence on sameness, and self-injurious behavior characterizing girls and increased stereotyped and restricted behavior characterizing boys. Future research should determine whether these elevated behaviors in girls are directly part of the autism presentation in girls or symptoms of co-occurring psychopathology. It is important for autism diagnostic measures to best capture the types of repetitive behavior girls may demonstrate.

Assessing subtypes of restricted and repetitive behaviour using the Adult Repetitive Behaviour Questionnaire-2 in autistic adults

Background

The majority of previous research into restricted and repetitive behaviours (RRBs) has focussed on children, partly due to a lack of suitable measures for RRBs in adults. This study aimed to explore the psychometric properties of the Adult Repetitive Behaviour Questionnaire-2 (RBQ-2A) in a large sample of autistic adults using a self-report questionnaire method.

Methods

The RBQ-2A and Autism-Spectrum Quotient (AQ) were administered online. Data from 275 autistic adults aged 18-66 (M = 36.56, SD = 12.24; 100 men and 171 women) were analysed using polychoric principal components analysis (PCA). Reliability and validity were assessed using Cronbach's alpha and correlation analyses.

Results

PCA resulted in two components of the RBQ-2A, interpretable as repetitive sensory and motor behaviours (RSMB) and insistence on sameness (IS). Both components showed acceptable internal consistency (α = .70 and .81 respectively) and were significantly moderately correlated with scores on the AQ (r _s  = .25 and .42). Participants' scores on IS were higher than their scores on RSMB. RSMB, but not IS, was negatively associated with age, particularly in older adults (≥ 50 years). There were no gender differences.

Conclusions

The RBQ-2A is a reliable and valid self-report measure of RRBs in the present sample of autistic adults. As one of the few measures of RRBs aimed at adults, it is suitable for adults with the ability to read and complete a self-report questionnaire. Results build on previous work with children using the Repetitive Behaviour Questionnaire-2 (RBQ-2).

The EU-AIMS Longitudinal European Autism Project (LEAP): design and methodologies to identify and validate stratification biomarkers for autism spectrum disorders

BACKGROUND

The tremendous clinical and aetiological diversity among individuals with autism spectrum disorder (ASD) has been a major obstacle to the development of new treatments, as many may only be effective in particular subgroups. Precision medicine approaches aim to overcome this challenge by combining pathophysiologically based treatments with stratification biomarkers that predict which treatment may be most beneficial for particular individuals. However, so far, we have no single validated stratification biomarker for ASD. This may be due to the fact that most research studies primarily have focused on the identification of mean case-control differences, rather than within-group variability, and included small samples that were underpowered for stratification approaches. The EU-AIMS Longitudinal European Autism Project (LEAP) is to date the largest multi-centre, multi-disciplinary observational study worldwide that aims to identify and validate stratification biomarkers for ASD.

METHODS

LEAP includes 437 children and adults with ASD and 300 individuals with typical development or mild intellectual disability. Using an accelerated longitudinal design, each participant is comprehensively characterised in terms of clinical symptoms, comorbidities, functional outcomes, neurocognitive profile, brain structure and function, biochemical markers and genomics. In addition, 51 twin-pairs (of which 36 had one sibling with ASD) are included to identify genetic and environmental factors in phenotypic variability.

RESULTS

Here, we describe the demographic characteristics of the cohort, planned analytic stratification approaches, criteria and steps to validate candidate stratification markers, pre-registration procedures to increase transparency, standardisation and data robustness across all analyses, and share some 'lessons learnt'. A clinical characterisation of the cohort is given in the companion paper (Charman et al., accepted).

CONCLUSION

We expect that LEAP will enable us to confirm, reject and refine current hypotheses of neurocognitive/neurobiological abnormalities, identify biologically and clinically meaningful ASD subgroups, and help us map phenotypic heterogeneity to different aetiologies.

Repetitive Behaviours and Restricted Interests in Individuals with Down Syndrome-One Way of Managing Their World?

This paper argues that the repetitive behaviour and restrictive interests (RBRI) displayed by individuals with Down syndrome have mostly positive functions. However, as research has developed from interests in Obsessional Compulsive Disorder or Autistic Spectrum Disorder, unfortunately a view has arisen that RBRI in individuals with Down syndrome are also likely to be pathological. This is particularly the case in adults. The paper reviews: (a) measures employed and the perspectives that have been used; (b) the development in typically developing individuals, those with Down syndrome, and those with other conditions associated with intellectual disability; (c) positive and possible negative effects of RBRI; and (d) the need for more research. The conclusion is that, for their level of development, RBRI are helpful for most individuals with Down syndrome.

Examining the Overlap between Autism Spectrum Disorder and 22q11.2 Deletion Syndrome

22q11.2 deletion syndrome (22q11.2DS) is a genomic disorder reported to associate with autism spectrum disorders (ASDs) in 15–50% of cases; however, others suggest that individuals with 22q11.2DS present psychiatric or behavioral features associated with ASDs, but do not meet full criteria for ASD diagnoses. Such wide variability in findings may arise in part due to methodological differences across studies. Our study sought to determine whether individuals with 22q11.2DS meet strict ASD diagnostic criteria using research-based guidelines from the Collaborative Programs of Excellence in Autism (CPEA), which required a gathering of information from three sources: the Autism Diagnostic Interview-Revised (ADI-R), the Autism Diagnostic Observational Schedule (ADOS), and a clinician’s best-estimate diagnosis. Our study examined a cohort of children, adolescents, and young adults (n = 56) with 22q11.2DS, who were ascertained irrespective of parents’ behavioral or developmental concerns, and found that 17.9% (n = 10) of the participants met CPEA criteria for an ASD diagnosis, and that a majority showed some level of social-communication impairment or the presence of repetitive behaviors. We conclude that strictly defined ASDs occur in a substantial proportion of individuals with 22q11.2DS, and recommend that all individuals with 22q11.2DS be screened for ASDs during early childhood.

Relationship between early motor milestones and severity of restricted and repetitive behaviors in children and adolescents with autism spectrum disorder

This study explored the relationships between the later age of achievement of early motor milestones, current motor atypicalities (toe walking), and the severity of restricted and repetitive behaviors (RRBs) in individuals with autism spectrum disorder (ASD). Parents of 147 children and adolescents with ASD (M_age  = 8.09 years, SD = 4.28; 119 males) completed an early developmental milestones questionnaire and the Social Responsiveness Scale as a measure of Insistence on Sameness (IS) and Repetitive Mannerisms (RM). Two hierarchical regression analyses were conducted to test whether RM and IS behaviors were predicted by early motor milestones, or current toe walking. The final model predicting RM accounted for 15% of the variance (F = 3.02, p = .009), with toe walking as a unique and independent predictor of RM scores (t = 3.568, p = .001). The final model predicting IS accounted for 19.1% of variance in IS scores (F = 4.045, p = .001), with chronological age (CA) (t = 2.92, p = .004), age when first standing (t = 2.09, p = .038), and toe walking (t = 2.53, p = .013) as unique independent predictors. Toe walking (t = 2.4, p = .018) and age when first sitting (t = 2.08, p = .04) predicted the severity of RRBs on the Autism Diagnostic Observation Schedule (F = 2.334, p = .036). Our study replicates previous findings on the relationship between concurrent motor impairments and RRBs, and provides the first evidence for the association between RRBs and age of attainment of early motor milestones. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1163-1168. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.