This study investigated the prevalence, and the developmental, behavior and emotional outcomes of 675 preschoolers with ASD with or without a history of regression, who participated in the Study to Explore Early Development (SEED). The SEED project is a cross-sectional case-control study that collected data between 2007 and 2011. Children's history of regression, adaptive skills, and behavior problems were assessed using the Autism Diagnostic Interview-Revised (ADI-R), the Vineland Adaptive Behavior Scales-Second Edition (Vineland-2), and the Child Behavior Checklist (CBCL), respectively; and children's developmental levels were assessed using the Mullen Scales of Learning (MSEL). Findings from this study indicated that 26% of children experienced social and language regression, and of those with regression, 76% had regained lost skills upon completion of the study. Compared to children without a history of regression, children with social regression demonstrated increased internalizing problems and decreased fine motor skills, and children with language regression demonstrated poorer language skills. Also, children with language and social regression displayed poorer adaptive communication skills than children without regression. Children who experienced regression in one area of development demonstrated better outcomes than those who experience regression in multiple areas. To conclude, children with regression are at risk for poorer outcomes during their preschool years.

Family navigator programs (i.e., programs to train family navigators) are becoming increasingly common among families of children with autism. Family navigators (i.e., individuals who help families access evaluations and/or services) may be parents of children with autism themselves or health professionals. Extant research has shown that family navigators can help families receive timely diagnostic evaluations and initial services. Yet, the development of family navigator programs is unclear; by exploring the input of families of children with autism, such programs can be responsive to family needs. In this study, we extend the extent literature by exploring the lived experiences of 12 parents of autistic children from low-resourced communities to inform the development of a family navigator program. Findings demonstrated that navigator programs need to prepare navigators to address barriers such as limited knowledge and difficulty accepting an autism diagnosis. Navigator programs should teach navigators to use strategies with families including educating families about services and connecting families with peer support. Program content should reflect direct services, government services, and advocacy strategies. Notably, for true improvements to service access for all autistic children, systemic changes are also needed in the service delivery systems. Implications are discussed.

Although the last decade has welcomed evidence that individuals with Rett syndrome (RTT) can communicate using alternative and augmentative communication (AAC), less is known about effective procedures for teaching various component skills required for expressive communication of individuals with complex communication needs. The purpose of the current study was to evaluate the effects of systematic individualized instruction procedures on the page-linking skills of individuals with RTT. A nonconcurrent multiple baseline design across participants was used to evaluate independent and accurate responding utilizing both a high-tech and low-tech AAC device for three participants. All sessions were conducted in the participants' homes by their parents with remote coaching from a researcher via telehealth. Results indicated that for all three participants, individualized procedures that included behavior chaining, differential reinforcement, and delayed prompting were effective for teaching page-linking in both a high-tech and a low-tech AAC device. Directions for future research and practice are discussed.

Rett syndrome is a severe neurodevelopmental disorder that results in both motor and language skill regression with a wide range of severity in symptom presentation. Communication intervention may be particularly challenging for this population due to the decline in speech, motor skills, and motor planning difficulties that characterize the disorder (Townend et al., 2020), often resulting in the need for augmentative and alternative communication (AAC) technology. Very limited research has evaluated communication interventions for individuals with Rett syndrome and even fewer have targeted expressive communication, an important skill required for improved autonomy and quality of life (Sigafoos et al., 2009; Townend et al., 2020). The current study sought to systematically replicate the Simacek et al. (2017) mand training procedures to teach three girls with Rett Syndrome to use AAC to make requests through caregiver coaching by researchers via telehealth. Results suggest that mand training was successful in increasing AAC use for all three participants. Barriers to intervention for this population and implications of results for future research and clinical practice are discussed.

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by executive dysfunction. Physical activity (PA) may improve executive dysfunction; however, specific barriers and facilitators to PA participation for adults with ADHD have not been formally documented, which was the aim of the present study. Thirty adults with ADHD completed virtual semi-structured interviews, which were analyzed thematically and guided by the Theoretical Domains Framework. Expressions of both barriers and facilitators to PA were identified. Themes such as executive dysfunction (described as forgetfulness, difficulty with sustained focus, and time management), poor self-esteem, and lack of motivation were seen as barriers to PA. Key facilitators were tied to the benefits of being physically active including improvements in executive functioning, mood, and mental health during and after activity, as well as the enjoyment of being active with others. To better support adults with ADHD in initiating physical activity, it is crucial to develop unique resources that are tailored to their specific needs. These resources should be designed to minimize barriers and maximize facilitators, while also supporting the awareness and acceptance of neurodiverse experiences.

Women with Tourette's syndrome (TS) continue to be under-researched, despite female sex being associated with increased tic-related impairment in adulthood. Existing literature indicates that individuals with TS are more likely than the general population to report self-stigma, but little is known about the subjective identities of women with TS and how this relates to psychological wellbeing. Semi-structured interviews were conducted via Zoom with a purposive sample of 11 females. All were diagnosed with TS and aged 18-28. Data was transcribed verbatim and thematic analysis applied. Five themes were established: "I'm not normal", "I just want to be me", I'm a "people pleaser", seeing oneself as an "outsider", and "it's just part of me…it's not going anywhere". Difficulties with self-acceptance and the autonomy to be one's true self were noted and appeared to be intensified by stereotypical gender roles and attempts to conceal tics. Findings also suggested that personal growth and feelings of mastery can be achieved through embracing TS as part of one's identity, or recognising it as just one aspect of the self. Psychological support focused on accepting and living with tics rather than reducing them may benefit this population and is currently difficult to access. Consideration should also be given to improving the availability of support groups where women with TS can meet others like themselves.

Mothers of school-aged children ages 3 to 17 years with developmental disabilities (DDs) commonly report sleep problems in their children associated with impaired maternal sleep. However, existing research relies heavily on mothers' self-reported sleep. This study aimed to determine the feasibility of objectively measuring child and mother sleep-wake patterns using actigraphy and videosomnography. This was an observational pilot study. Mothers wore actigraphy watches and video-recorded their child's sleep for 7 nights. Mothers also completed a 7-day sleep diary and questionnaires on sleep quality, depressive symptoms, stress, and child sleep problems. Ten mothers (32-49 years) and ten children with DDs (8-12 years) completed this study. Half of the children were boys with autism spectrum disorders. We successfully recruited 77% of eligible mothers for the study during the pandemic. Eight mothers successfully wore the actigraphy, and nine successfully video-recorded their child's sleep. Mothers rated their participation positively and considered the data collection protocol acceptable. While mothers' sleep patterns from actigraphy were mostly within recommendations, self-reported sleep quality was poor. Child's sleep estimates from videosomnography showed children slept substantially less than recommended sleep hours. Mothers also reported a high frequency of child sleep problems. Consistent with this pattern, mothers also endorsed elevated stress and depression. The use of actigraphy and videosomnography is feasible. Objective sleep measurement for mothers' and children's sleep is needed with self-report to measure multidimensional aspects of sleep and discrepancies between objective and self-report sleep measures. Future studies can use multi-methods sleep measures and work toward interventions that can improve family sleep and reduce mothers' stress and depression.

Graduate Records Examinations (GRE) remain an important criterion for admission to the graduate program. This study explored the predictive role of the GRE for college success among deaf students because most deaf and hard-of-hearing students experience lifelong difficulties in English language and literacy because of their different language acquisition processes. Additionally, the study examined the students' undergraduate grade point average (UGPA), first-semester grade point average (FSGPA), and graduating graduate grade point average (GGPA) to understand D/HH students' performance in a graduate program. Additionally, the study examined the use of the Wechsler Adult Intelligence Scale (WAIS) as a substitute for the GRE criterion for graduate admission. The findings' discussions offer suggestions for using GRE scores in admitting D/HH students to graduate academic programs across the United States.

The vast majority of individuals with Rett syndrome do not utilize natural speech and therefore require alternative and augmentative communication (AAC). The purpose of the current study was to investigate the use of high- and low-tech AAC modalities by three individuals with Rett syndrome given similar instruction for using both modalities. For all participants, the number of sessions to criterion and cumulative number of trials with independent requests during simultaneous or alternating instruction in the use of a high- and low-tech AAC modality were investigated. Parents conducted all sessions with remote coaching from a research assistant via telecommunication. Each participant exhibited idiosyncratic response patterns in terms of use of their high- and low-tech AAC modalities during instruction but ultimately demonstrated the ability to use both modalities to make requests. Implications for future research and practice pertaining to AAC of individuals with complex communication needs are discussed. This paper is a companion to Girtler et al. (2023).

The COVID-19 pandemic has brought significant changes across society. This Delphi study aimed to gain expert consensus on challenges faced and resource needs for autistic children during the COVID-19 pandemic. Round 1 of the Delphi method employed semi-structured interviews with experts (N = 24) which were thematically analysed in order to identify needs, resource targets and resource development. In a follow-up Round 2 survey participants rated emergent need and resource in order of priority. Round 2 provided consensus on challenges faced with anxiety, routine and wellbeing ranked most important. Direction on resource design was also obtained. Consensus on the challenges and resources was achieved and is being integrated into a needs-based transition resources toolkit. Future studies could make use of the Delphi method to quickly gain consensus on focus of needs in other contexts and communities.

As interest in derived relational responding has increased, so have the number of investigations evaluating interventions to promote the emergence of derived responding for individuals with autism, as well as other intellectual and developmental disabilities. However, much of the literature has focused on the relation of sameness, and less is known about interventions to facilitate derived responding in other relations. Systematic searches identified 38 studies contained in 30 articles that met inclusion criteria. These studies were analyzed according to their participants, assessment methods, experimental design, content taught, setting, teaching procedures, derived responses, outcomes, and reliability measures. The quality of the studies was measured using the Single Case Analysis and Research Framework (SCARF). The results of the current review indicate that many learners with autism spectrum disorder and other intellectual and developmental disabilities demonstrate derived relational responding beyond the relation of coordination across varied instructional content and teaching methodologies, but the quality and rigor of the published literature requires the results be interpreted with caution, leading to recommendations for future research.

To investigate the safety and feasibility of six sessions of Hybrid Assistive Limb (HAL) robot-assisted gait training (RAGT) integrated into an inpatient therapy concept and their influence on walking speed and gait parameters in adult CP patients.

Recognizing the crisis the COVID-19 pandemic represents to the Home- and Community-Based Services (HCBS) service system and the health, safety, and quality of life of people with intellectual and developmental disabilities (IDD), states temporarily amended their HCBS programs to strengthen service delivery. States are able to temporarily amend their HCBS 1915(c) waiver programs by submitting Appendix K: Emergency Preparedness and Response Waivers to the Centers for Medicare and Medicaid Services (CMS). The aim of this study was to examine if, and how, states increased their reimbursement rates for HCBS IDD waiver services during the COVID-19 pandemic. To do so, we analyzed 294 Appendix Ks which amended HCBS 1915(c) waivers for people with IDD between the start of the pandemic and April 2022. During the pandemic, 34 states and the District of Columbia increased reimbursement rates for 2,435 services provided by 82 HCBS waivers for people with IDD. Increase in reimbursement rates ranged from 3.5% to 160.7%, with an average increase of 23.3%. States most frequently increased reimbursement for supports to live in one's own home, residential habilitation, and health and professional services. In addition, 12 states and the District of Columbia offered one-time supplemental payments through 25 HCBS waivers for people with IDD. While increasing payments during the pandemic likely helped stabilize the HCBS service system during this period of crisis, what remains to be seen is how the IDD service system will function when this additional funding is discontinued.

Our main purpose in this study was to investigate the levels of and the relationship between familiarity, confidence, training, and use of problem behavior interventions by special education teachers working with learners with autism spectrum disorder (ASD) in school settings. A total of 80 special education teachers in South Carolina and Virginia completed an online survey. Results indicate a positive correlation between teachers' familiarity, confidence, training, and use of problem behavior interventions. Across all intervention categories, providing choices, prompting, modeling, and direct instruction received the highest rankings for familiarity, confidence, and use. In addition, our results reveal that familiarity and confidence in implementing these interventions differs across groups of special education teachers based on years of experience. The most frequently reported factors that limit the use of problem behavior interventions in school settings were competing responsibilities, the need to involve multiple people, the amount of time required, and the difficulty using interventions during typical routines. Implications for research and practice are discussed.

We designed and distributed a survey that assessed safety concerns experienced by direct service providers (DSPs) (N = 59) of adults with intellectual and developmental disabilities (IDD) in community-based group homes at a single human services organization. Results indicated relatively few safety concerns among the respondents from a list of 25 survey statements. Possible influences on the findings are presented such as safety training of the DSPs, comprehensive safety guidelines in place at the group homes, and conditions occasioned by the COVID-19 pandemic. Current safety research in IDD supports the necessity of assessment to inform prevention and intervention strategies.

Recent research has begun to explore the specific social challenges experienced by persons with Tourette syndrome (TS); however, it does not specifically address the challenges that often arise interpersonally as part of people's communicative interactions and these interactions socially construct the individual and collective well-being of all involved. This study conducted semi-structured interviews with 18 adults who identified as having TS in order to investigate the ways in which others respond behaviorally to TS behaviors and the ways TS behaviors are misinterpreted within interpersonal interactions. Thematic analysis was used to identify themes common within participant responses. All participants reported receiving unwanted attention from others in response to their TS symptoms. Unwanted attention was further divided into six emergent subthemes, including verbal harassment, physical abuse, staring, general bullying, getting into trouble, and being kicked out. Three types of misunderstandings were also reported in interpersonal interactions: misunderstanding communicative intention, misunderstanding TS, and misunderstanding the cause of TS behaviors. Applying attribution theory, it is determined that it is ultimately the misattribution of communicative intent to TS behaviors that causes many misunderstandings reported by adults with TS and leads to a plethora of interpersonal, communicative challenges. Importantly, these misunderstandings are what ultimately contribute to much of the unwanted attention described by the participants in this study and documented in previous work, highlighting the value of a greater awareness of how misunderstandings take place with respect to TS.

The study was aimed to define swallowing related problems of toddlers with Down syndrome (DS) by comparing toddlers with typically developing children (TDC). A total of 127 children (96 DS, 31 TDC), and their mothers included in the study. The presence of chewing disorders, food selectivity, drooling, coughing during swallowing was scored as absent' or 'present'. The Pediatric version of the Eating Assessment Tool-10 (PEDI EAT-10) was used to determine dysphagia symptom severity, and the Turkish version of the Feeding/Swallowing Impact Survey (T-FS-IS) was used to measure the impact of swallowing disorders on caregivers. Mothers of DS reported higher rates of chewing disorders (n = 39, 40.6%), drooling (n = 30, 31.3%) and coughing during swallowing (n = 50, 41.7%) than mothers of TDC (p < 0.01). The mean PEDI-EAT-10 score of children with DS was higher than TDC (p = 0.006). There were significant differences between groups in terms of T-FS-IS. Moderate to strong correlations were detected between PEDI-EAT-10 and total and subscale scores from T-FS-IS (p < 0.001). This prospective study defines swallowing related problems of toddlers with DS. The study results highlight the importance of early investigation of (i) swallowing concerns in children with DS, and (ii) caregivers' quality of life to define swallowing problems and plan an appropriate swallowing related management program.

Severe developmental disability in children affects the life of the child and entire household. We conducted a qualitative study to understand how caregivers manage severe developmental disabilities in children in rural Africa. Families and six children (out of 15 children) who had serious permanent sequelae from a cerebral infection in Handeni, Tanzania, were contacted and invited to a workshop to recount their experience living with severe developmental disabilities. After consent, individual interviews were conducted first through recording of individual digital stories and then through individual semi-structured interviews. Pre-determined key categories were used to analyse the data. Our results showed that developmental disabilities required constant care and reduced the autonomy of the children. Schooling had not been attempted or was halted because of learning problems or inability to meet specialized school costs. Parents were under constant physical, emotional and financial stress. Their occupational earnings decreased. Some families sold their assets to survive. Others began to rely on relatives. Understanding the consequences of developmental disability helps to identify where social support should be focused and improved.

Many individuals diagnosed with intellectual and developmental disabilities (IDD) are uncooperative during routine dental exams, leading to poor oral health in this population. Few studies have evaluated methodologies for preparing dental students and professionals to work effectively with patients diagnosed with IDD. In this study, experimenters used remote behavioral skills training (BST) to train dental students and professionals how to implement a practical intervention that included tell-show-do, contingent praise, and noncontingent reinforcement. Results suggested that group training conducted via videoconferencing was effective for teaching six of seven participants to implement the intervention in the absence of post-training feedback. This approach appears useful for quickly and efficiently training current and future dental professionals to implement behavior techniques to promote patient compliance.

The COVID-19 outbreak affected the daily lives of individuals with Down syndrome, who were considered to have a higher risk of severe infection. While several studies have reported mental health issues in children and/or parents in the general population, no study has focused on people with Down syndrome and their caregivers. This study investigated the disinfection behaviors of individuals with Down syndrome and their caregivers' stress. A cross-sectional retrospective survey was conducted in October 2020. Caregivers of children and adults with Down syndrome were administered questionnaires including measures for practiced disinfection behavior in children, caregiver's child-related stress, and psychological distress. About half of the respondents' children practiced hand hygiene and mask-wearing behaviors, while physical distancing was performed less frequently. Habitual practices in physical distancing are affected by intellectual function. Logistic regression showed that caregivers' stress was associated with the irritability of individuals with the disorder (adjusted odds ratio [OR] = 8.44, 95% confidence interval [CI] 1.69-42.09) and the burden of infection-prevention behaviors for people with Down syndrome (adjusted OR = 4.26, 95% CI 1.88-9.65). This study showed the characteristics of disinfection behaviors in individuals with Down syndrome and associated factors for serious caregiver stress.

Although the benefits of regular physical activity are clearly expressed, children with Autism Spectrum Disorder (ASD) are less physically active than their typically developing peers. Recent empirical studies have revealed that the level of physical activity of children with ASD has further decreased during the novel coronavirus (COVID-19) pandemic, which has adversely affected the whole world. The aim of this study was to evaluate the potential efficacy of a Zoom-delivered physical activities for children with Autism Spectrum Disorder (ASD). Twenty-two families (parent and child dyads) participated in the study. Families were assigned randomly to an experimental group (n = 11) and a control group (n = 11). Families in the experimental group were engaged in 10 weeks of the Zoom-delivered physical activities. Data were collected using multiple data collection strategies (Personal Information Form- Leisure Time Exercise Questionnaire-Semi-Structured Interview). After the Zoom-delivered physical activities, a significant increase was observed in the physical activity level of children with ASD in the experimental group ( = 95.396,  = 0.000,  = 0.834). Parents reported that Zoom-delivered physical activities are a viable and useful intervention to increase the level of physical activity of children with ASD. The findings suggest that Zoom-delivered physical activities merit further investigation as an intervention to increase physical activity in children with ASD.

This study examined how students with orthopedic impairments experienced strategies identified in the literature to support 'inclusion'. An interpretative phenomenological analysis research approach was used, and six students with orthopedic impairments (age 10-14 years) served as participants. Data sources were written prompts, semi-structured, audiotaped interviews, and reflective interview notes. Based on thematic data analysis, four themes were constructed: "It's kind of embarrassing": experiences with support; "I don't want to be different": equipment, activity, and rule modifications; "I like to be a part of the conversation": autonomy and choice in PE; and "I would rather be like the other students": discussing disability. The experiences portrayed through these themes highlighted the differential effects of these explicated strategies, where each strategy contributed to feelings of inclusion, as well as marginalization among participants. As such, the findings indicated that 'inclusive' strategies should not be considered as blanket recommendations; instead, attempts to promote 'inclusion' of students with disabilities should start with a reflexive look at the unique needs of each individual student.

Using telehealth as a mode of service delivery has the potential to address some long-standing challenges in early intervention (EI) services such as waiting lists to access services. Yet, little is known about parent perceptions of telehealth in EI based on their lived experiences partnering with EI practitioners. The purpose of this study was to explore parent perceptions on using telehealth, especially on family-professional partnerships and coaching. Interviews were conducted with 15 parents of children receiving EI services via telehealth from June to August of 2021. Almost half of the participants reflected under-represented racial and ethnic backgrounds. Constant comparative analysis and emergent coding were used for data analysis. The findings showed that the advantages outnumbered the disadvantages regarding telehealth. Participants reported that telehealth provided a safe and flexible option and eliminated the wait to access EI services. However, participants identified some disadvantages to telehealth including telehealth precluded substantive interactions with therapists and limited access to technology. The findings also indicated that telehealth enhanced family-professional partnerships. Nearly all participants valued coaching during telehealth. Participants suggested initial supports to facilitate EI via telehealth, including stable internet access, telehealth training, and an initial in-person visit. Implications for research and practice are discussed.

There is a growing body of evidence supporting the use of telehealth to provide parent training in behaviour analytic interventions and researchers have begun to focus on international demonstrations of this model. The current study assessed the efficacy of a training package focused on naturalistic teaching strategies designed to upskill parents of children with autism spectrum disorder and provide them with ready to use strategies to increase social communication behaviours across verbal operants. Two parent-child dyads were trained to increase mand, tact and intraverbals during play. Parents displayed increases in fidelity for each strategy and viewed the training favourably. Both children showed gains across verbal operants, as captured by a multiple baseline across behaviours design.

This study evaluates the effectiveness of a brief functional analysis and functional communication training conducted via telehealth. Three interventionist-child dyads took part in the study including one speech and language pathologist and two school teaching assistants, each working with one child with autism spectrum disorder. Interventionists were trained using didactic training to implement a brief functional analysis as well as synchronous coaching from a BCBA to implement functional communication training. A multiple baseline across participants design was utilised to evaluate if interventionists could implement functional communication training to decrease challenging behaviours that included aggression, elopement and disruption. Sessions concluded earlier than planned due to school closures mandated by the COVID-19 outbreak for two of the three participants; however, existing data provide evidence that telehealth is a valid model for enabling clinicians to work in collaboration with school personnel to effectively deliver assessment and intervention procedures remotely via telehealth.

[This corrects the article DOI: 10.1007/s10882-022-09859-4.].

Handwashing is a vital skill for maintaining health and hygiene. For individuals with intellectual and developmental disabilities (IDD), such as autism spectrum disorder, evidence-based strategies, such as prompting and task analysis, may be effective in teaching these skills. Due to the shortage of experts who teach individuals with IDD skills such as handwashing, staff working with children need a means of ensuring these instructional strategies are implemented with fidelity. This study examined the effects of a tablet-based application that used artificial intelligence (GAINS®) on four behavior technicians' implementation of least-to-most prompting, total task chaining, and time delay during an acquisition of handwashing program with young children with autism. All four technicians increased fidelity immediately upon using GAINS and all four technicians reached mastery criteria within the shortest number of sessions possible. One child participant met mastery criteria, two showed some gains, and one demonstrated a high degree of variability across sessions. Limitations of the least-to-most prompting procedure, user design, considerations and directions for future research and practice are discussed.

Interventions based upon applied behaviour analysis (ABA) have been shown to be best practice for children with autism spectrum disorder. However, in many parts of the world there is a shortage of appropriately trained behaviour analysts. Telehealth is a potential solution to increasing access to ABA. Our study assessed the use of telehealth to provide parent training in naturalistic teaching strategies designed to increase child communication skills. Five parent child dyads took part in the training, utilising didactic training and synchronous coaching. Parents could be trained to a high level of fidelity and viewed the training favourably. Children showed variable gains in communication and improved positive affect. The project was cost effective in comparison with traditional training models.

The COVID-19 pandemic has led to a radical lifestyle change, which may unintendedly change physical activity levels. We aimed to perform a systematic review to investigate the physical activity changes in people with neurological diseases, and to examine the relationship between physical activity and disease symptoms, and psychosocial factors. The review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A systematic search of the literature across five databases (PubMed, CINAHL, Web of Science, SCOPUS, and Cochrane Library) was carried out using the keywords relating to COVID-19, physical activity, sedentary behaviour, exercise, and the name of the neurological diseases. The systematic search was updated on 4 February 2021 with the same keywords. Fourteen studies (n = 7662 persons with neurological diseases, n = 1663 healthy controls) were eligible for this review. The study populations were Parkinson disease (n = 7), dementia (n = 1), multiple sclerosis (n = 1), spinal cord injury (n = 1), hereditary spastic paraplegia (n = 1), neuromuscular diseases (n = 1), Charcot-Marie-Tooth neuropathy (n = 1), and epilepsy (n = 1). Thirteen studies reported a decreased physical activity level, one study reported a high interruption rate of physiotherapy/rehabilitation. Furthermore, the physical activity reduction was associated with worse disease symptoms, depression, perceived health, and mental and physical components of quality of life. The COVID-19 pandemic has a negative impact on the physical activity levels of people with neurological diseases, and this change was related to the worsening of disease symptoms and psychosocial factors.  A protocol of the review was registered with the PROSPERO database (CRD42020207676).

Rett syndrome (RTT) is a rare, late detected developmental disorder associated with severe deficits in the speech-language domain. Despite a few reports about atypicalities in the speech-language development of infants and toddlers with RTT, a detailed analysis of the pre-linguistic vocalisation repertoire of infants with RTT is yet missing. Based on home video recordings, we analysed the vocalisations between 9 and 11 months of age of three female infants with typical RTT and compared them to three age-matched typically developing (TD) female controls. The video material of the infants had a total duration of 424 min with 1655 infant vocalisations. For each month, we (1) calculated the infants' canonical babbling ratios with CBR, i.e., the ratio of number of utterances containing canonical syllables to total number of utterances, and (2) classified their pre-linguistic vocalisations in three non-canonical and four canonical vocalisation subtypes. All infants achieved the milestone of canonical babbling at 9 months of age according to their canonical babbling ratios, i.e. CBR ≥ 0.15. We revealed overall lower CBRs and a lower proportion of canonical pre-linguistic vocalisations consisting of well-formed sounds that could serve as parts of target-language words for the RTT group compared to the TD group. Further studies with more data from individuals with RTT are needed to study the atypicalities in the pre-linguistic vocalisation repertoire which may portend the later deficits in spoken language that are characteristic features of RTT.