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Lay Abstract: Most support programmes for Autistic children are available only after they are diagnosed. Research suggests that parenting supports may be helpful for parents and their infants, when provided in the first 2 years of life - before a formal diagnosis is given, but when information suggests an infant is more likely to be Autistic. However, we do not know how acceptable these types of supports might be to the Autistic and autism communities. We asked 238 Autistic and non-autistic people - some of whom were parents, and some of whom were professionals working in research, health and education - about their perspectives on very-early supports. People generally agreed that it could be acceptable to work with parents to help them understand and support their child's specific needs and unique ways of communicating. People suggested a variety of support strategies could be acceptable, including parent education, changing the environment to meet an infant's needs, and creating opportunities for infants' to make choices and exercise control. People preferred respectful and accurate language - including the term 'support' (rather than 'intervention') and 'early-in-life' (rather than 'at-risk' of autism, or 'pre-emptive' when describing developmental stage). Continuing to work with community members will help to make sure autism support programmes are relevant and helpful., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Several authors have been involved in the development (JG, LRW, SSM) and/or evaluation (AA, AJOW, CAB, CG, JG, JS, KH, LRW, SSM) of support programmes for young Autistic children. JG and LH receive royalties and/or other benefits from training related to a specific support model. AJOW, JG, JS, KF, LH, RJ and SSM are/have been employed by and/or have/have had roles with service providers that support young Autistic children. These potential conflicts of interest were managed within the research team by engaging Autistic and non-Autistic researchers and community members with no known conflicts of interest (ANG, ASR, CC, EF, KEG, KEM, LNA, LJK, PD).

Parenting is a rewarding experience but is not without its challenges. Parents of Autistic children face additional challenges, and as a result can experience lower levels of wellbeing and more mental health problems (i.e., depression, anxiety, stress). Previous studies have identified concurrent correlates of wellbeing and mental health. However, few have investigated predictors of subsequent wellbeing and mental health, or of change over time, among parents of pre-school aged autistic children. We examined child-, parent-, and family/sociodemographic factors associated with change in parents' mental health and wellbeing across three timepoints (spanning approximately one year) among 53 parents of Autistic pre-schoolers (M = 35.48, SD = 6.36 months. At each timepoint, parents reported lower wellbeing and greater mental health difficulties compared to normative data. There was no significant group-level change over time in parent outcomes. However, individual variability in short-term (~ 5 months) wellbeing and mental health change was predicted by a combination of child- and parent-related factors, while variability in medium-term (~ 10 months) change was predicted by parent factors alone. Parents' description of their child and their relationship predicted change in both wellbeing and mental health. Furthermore, participating in a parent-mediated intervention (available to a subgroup) was a significant predictor of change in wellbeing. Our findings highlight potentially modifiable factors (e.g., learning healthier coping strategies) that may positively impact both short- and medium-term change in parental outcomes., (© 2024. The Author(s).)

Purpose: While research indicates that both the core features of autism and associated developmental skills influence adaptive behaviour outcomes, results to date suggest greater influence of the latter than the former, and little attention has been given to how the interaction of both together might impact functional disability. Seeking to expand understanding of associations between young children's core social autism features, developmental skills, and functional ability/disability, we specifically tested whether early developmental skills might have a moderating effect on the association between early social features and subsequent functional disability., Methods: Data from 162 preschool children were available for this study. These included time-1 measures of social autism features (ADOS-Social Affect score) and developmental skills (MSEL-Developmental Quotient; DQ), and a measure of functional ability/disability (VABS-Adaptive Behaviour Composite; ABC) available at follow-up 1-year later (time-2)., Results: Time-1 ADOS-SA and MSEL-DQ scores were concurrently associated with one another, and both prospectively associated with time-2 VABS-ABC scores. Examination of partial correlations (i.e., controlling for MSEL-DQ) demonstrated that the association of time-1 ADOS-SA and time-2 VABS-ABC was accounted for by shared variance with DQ. Formal moderation analysis returned a non-significant overall interaction term, but showed a lower-bound region of significance whereby the association of time-1 ADOS-SA with time-2 VABS-ABC was significant for children with baseline DQ ≤ 48.33., Conclusion: Our results add to a body of empirical evidence consistent with an understanding of the needs of and resources available to autistic people through a 'cognitive compensation' lens., (© 2023. The Author(s).)

We explored associations among the core behavioural features and developmental/cognitive abilities of 155 autistic children, assessed between ages 13-67 months and again around 1-year later to understand predictive directionality. Bidirectional, cross-domain association was apparent, albeit with stronger direction of effect from earlier cognition to later autism features (than vice versa). Exploratory sub-domain analysis showed that early non-verbal developmental/cognitive abilities (only) predicted subsequent social- and restricted/repetitive autism features, whereas early social features (only) predicted both subsequent verbal and non-verbal abilities. Although observational study design precludes causal inference, these data support contemporary notions of the developmental interconnectedness of core autism presentation and associated abilities-that behavioural autism features may influence cognitive development, but are likely also influenced by an individuals' cognitive capacity., (© 2022. The Author(s).)

We tested the potential for Gazefinder eye-tracking to support early autism identification, including feasible use with infants, and preliminary concurrent validity of trial-level gaze data against clinical assessment scores. We embedded the ~ 2-min 'Scene 1S4' protocol within a comprehensive clinical assessment for 54 consecutively-referred, clinically-indicated infants (prematurity-corrected age 9-14 months). Alongside % tracking rate as a broad indicator of feasible assessment/data capture, we report infant gaze data to pre-specified regions of interest (ROI) across four trial types and associations with scores on established clinical/behavioural tools. Most infants tolerated Gazefinder eye-tracking well, returning high overall % tracking rate. As a group, infants directed more gaze towards social vs. non-social (or more vs. less socially-salient) ROIs within trials. Behavioural autism features were correlated with increased gaze towards non-social/geometry (vs. social/people) scenes. No associations were found for gaze directed to ROIs within other stimulus types. Notably, there were no associations between developmental/cognitive ability or adaptive behaviour with gaze towards any ROI. Gazefinder assessment seems highly feasible with clinically-indicated infants, and the people vs. geometry stimuli show concurrent predictive validity for behavioural autism features. Aggregating data across the ~ 2-min autism identification protocol might plausibly offer greater utility than stimulus-level analysis alone., (© 2024. The Author(s).)

Both the amount and responsiveness of adult language input contribute to the language development of autistic and non-autistic children. From parent-child interaction footage, we measured the amount of adult language input, overall parent responsiveness, and six discrete parent responsive behaviours (imitations, expansions, open-ended questions, yes/no questions, comments and acknowledgements) to explore which types of responsiveness predicted autistic preschoolers' language five months later, after controlling for adult language input. We found expansions and particularly imitations to be more important for later language than overall responsiveness. This study emphasises the need to capture what exactly about parent language input influences child language acquisition, and adds to the evidence that imitating and expanding early language might be particularly beneficial for autistic preschoolers., (© 2022. The Author(s).)

Lay Abstract: Support for autistic children early in life should help them to lead flourishing lives. However, many of the early intervention programmes for young autistic children are time-consuming and costly for families. These programmes are also often conducted in settings that are not closely matched to real life. We spoke to 23 parents (of 22 autistic children) to understand their experiences of their children's involvement in early intervention. Parents told us they were grateful for the opportunity, that they had 'hit the jackpot', and their children had 'gained so much' from the programme. They seemed to value the service because it made them feel safe and secure during an uncertain time in their children's lives. Parents told us they trusted staff, felt that they weren't 'doing it alone', and this 'took that pressure off' and helped them feel empowered. They also spoke of feelings of safety from being linked to the university research programme which offered 'accountability' and 'integrity'. Parents' comments showed a strong commitment to the early intervention model and staff - but also common feelings of abandonment and disempowerment as their child's time with the programme came to an end and they went 'back to the real world' and needed to find new supports for their children. These parents' insights should help to inform the design and delivery of community supports for preschool-aged autistic children and their families, which match the reality of their lived experiences.

Natural Language Sampling (NLS) offers clear potential for communication and language assessment, where other data might be difficult to interpret. We leveraged existing primary data for 18-month-olds showing early signs of autism, to examine the reliability and concurrent construct validity of NLS-derived measures coded from video-of child language, parent linguistic input, and dyadic balance of communicative interaction-against standardised assessment scores. Using Systematic Analysis of Language Transcripts (SALT) software and coding conventions, masked coders achieved good-to-excellent inter-rater agreement across all measures. Associations across concurrent measures of analogous constructs suggested strong validity of NLS applied to 6-min video clips. NLS offers benefits of feasibility and adaptability for validly quantifying emerging skills, and potential for standardisation for clinical use and rigorous research design., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

While theory supports bidirectional effects between caregiver sensitivity and language use, and infant language acquisition-both caregiver-to-infant and also infant-to-caregiver effects-empirical research has chiefly explored the former unidirectional path. In the context of infants showing early signs of autism, we investigated prospective bidirectional associations with 6-min free-play interaction samples collected for 103 caregivers and their infants (mean age 12-months; and followed up 6-months later). We anticipated that measures of caregiver sensitivity/language input and infant language would show within-domain temporal stability/continuity, but also that there would be predictive associations from earlier caregiver input to subsequent child language, and vice versa. Caregiver sensitive responsiveness (from the Manchester Assessment of Caregiver-Infant interaction [MACI]) predicted subsequent infant word tokens (i.e., amount of language, coded following the Systematic Analysis of Language Transcripts [SALT]). Further, earlier infant Mean Length of Utterance (MLU; reflecting language complexity, also derived from SALT coding) predicted later caregiver MLU, even when controlling for variability in infant ages and clear within-domain temporal stability/continuity in key measures (i.e., caregiver sensitive responsiveness and infant word tokens; and infant and caregiver MLU). These data add empirical support to theorization on how caregiver input can be both supportive of, and potentially influenced by, infant capacities, when infants have social-communication differences and/or communication/language delays suggestive of possible emerging autism., (© 2022 The Authors. Autism Research published by International Society for Autism Research and Wiley Periodicals LLC.)

Lay Abstract: Parental Expressed Emotion refers to the intensity and nature of emotion shown when a parent talks about their child, and has been linked to child behaviour outcomes. Parental Expressed Emotion has typically been measured using the Five-Minute Speech Sample; however, the Autism-Specific Five-Minute Speech Sample was developed to better capture Expressed Emotion for parents of children on the autism spectrum . In each case, parents are asked to talk for 5 min about their child and how they get along with their child. Parents' statements are then coded for features such as number of positive and critical comments, or statements reflecting strong emotional involvement. While both the Five-Minute Speech Sample and Autism-Specific Five-Minute Speech Sample have been used with parents of autistic school-aged children, their relative usefulness for measuring Expressed Emotion in parents of preschool-aged children - including their links to child behaviour problems in this group - is unclear. We collected speech samples from 51 parents of newly diagnosed autistic preschoolers to investigate similarities and differences in results from the Five-Minute Speech Sample and Autism-Specific Five-Minute Speech Sample coding schemes. This included exploring the extent to which the Five-Minute Speech Sample and Autism-Specific Five-Minute Speech Sample, separately, or together, predicted current and future child behaviour problems. While the two measures were related, we found only the Autism-Specific Five-Minute Speech Sample - but not the Five-Minute Speech Sample - was related to child behavioural challenges. This adds support to the suggestion that the Autism-Specific Five-Minute Speech Sample may be a more useful measure of parental Expressed Emotion in this group, and provides a first step towards understanding how autistic children might be better supported by targeting parental Expressed Emotion.

Background: There is growing understanding of the potential benefits of a multi-method approach to accurately capture language skills of children on the autism spectrum. Tools such as Language ENvironment Analysis (LENA) provide an efficient means of capturing and analysing early child vocalizations (CVs) and the language learning environment. While developed to capture whole-day recordings of child language in naturalistic settings, there is potential utility in capturing, but little knowledge about, primary LENA metrics-including CVs and conversational turns (CTs)-and novel metrics, such as vocalization ratios (VRs), sampled in clinical practice settings where children are often seen. Moreover, recent research indicates that the novel VR may offer a broad indicator of children's developmental level, beyond just their language abilities, a hypothesis yet to be investigated in a large sample of children for whom the LENA was designed (i.e., pre-schoolers)., Aims: To explore the extent to which primary and novel LENA metrics collected during brief one-to-one clinical interaction was a useful indicator of developmental outcomes for children on the autism spectrum., Methods & Procedures: Participants were recruited as part of an on-going research programme evaluating early intervention outcomes (n = 99; age 14-47 months). Language samples were collected at intake (T1) using the wearable LENA Digital Language Processors during a one-to-one, play-based assessment with a clinician. Direct (Mullen Scales of Early Learning-MSEL) and parent-report (Vineland Adaptive Behavior Scales-VABS) measures of verbal and non-verbal skills were also collected at intake (T1) and again at exit (T2), approximately 12 months later., Outcomes & Results: Few correlations were observed between child measures and CVs, a primary LENA metric. The novel VR metric was associated with concurrent direct assessment (MSEL) (and to a lesser extent parent report; VABS) measures of verbal and non-verbal skills, with moderate positive correlations found between VRs and all directly assessed subscale scores. However, VRs did not uniquely contribute to the prediction of child outcomes when baseline skills were also considered., Conclusions & Implications: The novel VR may provide an insight into autistic children's overall development in addition to their language ability, suggesting that even when collected in a short recording format, LENA might be a useful component of a multi-method assessment approach., What This Paper Adds: What is already known on the subject To accurately capture language skills of children on the autism spectrum, multi-method approaches, including natural language sampling, are recommended. Tools such as LENA provide an efficient means of capturing and analysing naturalistic child language and the language learning environment. What this paper adds to existing knowledge This study demonstrates the potential benefits, and limitations, of using LENA to augment assessment of young children on the autism spectrum. Specifically, LENA provides a complementary, and low burden, method for capturing child language samples. What are the potential or actual clinical implications of this work? Novel metrics, such as the VR, collected during brief clinical interactions might be a useful component of a multi-method assessment approach for children on the autism spectrum., (© 2021 Royal College of Speech and Language Therapists.)

Importance: Intervention for individuals with autism spectrum disorder (ASD) typically commences after diagnosis. No trial of an intervention administered to infants before diagnosis has shown an effect on diagnostic outcomes to date., Objective: To determine the efficacy of a preemptive intervention for ASD beginning during the prodromal period., Design, Setting, and Participants: This 2-site, single rater-blinded randomized clinical trial of a preemptive intervention vs usual care was conducted at 2 Australian research centers (Perth, Melbourne). Community sampling was used to recruit 104 infants aged 9 to 14 months showing early behaviors associated with later ASD, as measured by the Social Attention and Communication Surveillance-Revised. Recruitment occurred from June 9, 2016, to March 30, 2018. Final follow-up data were collected on April 15, 2020., Interventions: Infants were randomized on a 1:1 ratio to receive either a preemptive intervention plus usual care or usual care only over a 5-month period. The preemptive intervention group received a 10-session social communication intervention, iBASIS-Video Interaction to Promote Positive Parenting (iBASIS-VIPP). Usual care comprised services delivered by community clinicians., Main Outcomes and Measures: Infants were assessed at baseline (approximate age, 12 months), treatment end point (approximate age, 18 months), age 2 years, and age 3 years. Primary outcome was the combined blinded measure of ASD behavior severity (the Autism Observation Scale for Infants and the Autism Diagnostic Observation Schedule, second edition) across the 4 assessment points. Secondary outcomes were an independent blinded clinical ASD diagnosis at age 3 years and measures of child development. Analyses were preregistered and comprised 1-tailed tests with an α level of .05., Results: Of 171 infants assessed for eligibility, 104 were randomized; 50 infants (mean [SD] chronological age, 12.40 [1.93] months; 38 boys [76.0%]) received the iBASIS-VIPP preemptive intervention plus usual care (1 infant was excluded after randomization), and 53 infants (mean [SD] age, 12.38 [2.02] months; 32 boys [60.4%]) received usual care only. A total of 89 participants (45 in the iBASIS-VIPP group and 44 in the usual care group) were reassessed at age 3 years. The iBASIS-VIPP intervention led to a reduction in ASD symptom severity (area between curves, -5.53; 95% CI, -∞ to -0.28; P = .04). Reduced odds of ASD classification at age 3 years was found in the iBASIS-VIPP group (3 of 45 participants [6.7%]) vs the usual care group (9 of 44 participants [20.5%]; odds ratio, 0.18; 95% CI, 0-0.68; P = .02). Number needed to treat to reduce ASD classification was 7.2 participants. Improvements in caregiver responsiveness and language outcomes were also observed in the iBASIS-VIPP group., Conclusions and Relevance: Receipt of a preemptive intervention for ASD from age 9 months among a sample of infants showing early signs of ASD led to reduced ASD symptom severity across early childhood and reduced the odds of an ASD diagnosis at age 3 years., Trial Registration: http://anzctr.org.au identifier: ACTRN12616000819426.

Lay Abstract: We know that parents of autistic children experience poorer mental health and lower well-being than parents of non-autistic children. We also know that poorer mental health among parents of autistic children has been observed across different cultures. Most research focuses on Western cultures, so we know little about parental mental health and well-being of parents from different cultural backgrounds; yet, it is likely that cultural background contributes to how parents view their child's condition and respond to the diagnosis. Here, we compared mental health, quality of life and well-being between families raising an autistic child from Australian backgrounds to families from South-East Asian backgrounds. All children in the current study were receiving the same community-based early intervention. When compared to the general population, parents had poorer mental health overall, but there were no differences between the two groups of parents. However, parents from South-East Asian backgrounds reported higher well-being and fewer difficulties associated with their child's autism. These findings suggest that cultural background likely influences not only parent's view of, and response to, their child's autism, but also their own sense of well-being. As researchers and clinicians working with families of autistic children, we should more explicitly consider family's cultural background within our work.

Lay Abstract: Raising a child with autism has been linked to mental health difficulties. Poor parental mental health is likely influenced by various factors - including child-, parent-, and family/socioeconomic characteristics. However, little is known about what influences and promotes well-being (as opposed to mental health) among parents of young, newly diagnosed autistic children who may be particularly vulnerable. We examined child-, parent-, and family/socioeconomic factors associated with each of mental health and well-being in a sample of 136 parents of pre-school-aged children. Parental mental health was linked to both child- (i.e. autism symptom severity) and parent-related factors (i.e. personality traits reflecting a tendency to experience negative emotions). By contrast, in additional to mental health difficulties, which were linked to well-being, only other parent-related characteristics (and not child characteristics) were related to well-being. These included personality traits reflecting a tendency to be more extraverted/sociable, and also mindfulness. Other child-related and family/socioeconomic context factors (including household income, parental education level) were not linked to parental mental health or well-being in this sample. These results support the idea that poorer mental health and well-being are not simply the opposite of one another. That is, while these two factors were related, they were linked to different personal characteristics. Perhaps most importantly, the link between well-being and mindfulness - a personal characteristic that parents can improve - suggests mindfulness-based interventions may be helpful in directly supporting parental well-being in the context of raising a young child with autism.

Background: The early identification and diagnosis of autism is critical to ensure access to appropriate early intervention and support. Few studies have examined the association between potentially modifiable characteristics of the service system and timelier diagnosis., Methods: An online survey was conducted to examine parental experiences of service pathways to an autism diagnosis for their child, and to identify child, family, and service level characteristics that predict the age and timeliness of diagnosis. Participants included 107 parents of children with autism who were diagnosed by 7 years of age and a smaller subgroup of 29 parents who were diagnosed after 7 years of age., Results: Parents of younger children reported that, on average, it took approximately 12 months and 8 professional consultations to receive a confirmed diagnosis for their child. Parents of older children, as well as those who reported they were a sole caregiver, or were advised by professionals to 'wait and see', reported more time between first raising concerns and diagnosis., Conclusions: The findings reiterate the importance of proactive professional responses to parental concerns. They also highlight the need for standardised screening and assessment and professional development and training to build capacity in the sector to deliver timely and accurate autism diagnoses., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background and Aims: Although bilingualism is a common worldwide phenomenon, limited research has considered the experiences of children with autism growing up in bilingual environments. Here, we investigated the potential influence of parental bilingualism, and native vs. non-native language use, on responsiveness to children's communication attempts during parent-child interactions where the child had autism. Specifically, we investigated the amount of parent responses to child verbal communication ( frequency ) and the promptness of these responses ( temporal synchrony )., Methods: Participants were 22 monolingual and 20 bilingual parents and their children with autism aged 2-6 years, recruited from a multicultural, metropolitan city where English is the dominant language. Extending from our previous report on this sample, we identified the frequency and temporal synchrony of parent responses from filmed 10-minute free-play sessions. Monolingual parents were videoed during one free-play session in English. Bilingual parents were videoed during two free-play sessions; one in their native language and one in English. We compared the frequency and temporal synchrony of parental responses across monolingual and bilingual parent groups and, for bilingual parents, across native vs. non-native (English) language interaction samples. Finally, we examined how other measures of bilingual parents' non-native language proficiency were associated with interaction responsiveness measures., Results: When using their native language, bilingual parents demonstrated reduced frequency of responsiveness (even when controlling for opportunities provided by the child) and less temporal synchrony to child communication compared to English-speaking monolingual parents. Bilingual parents were also less frequently responsive (but not less temporally synchronous) during their native- compared to during their non-native (English) language interactions. Moreover, for bilingual parents, more frequent responsiveness to child communication bids when interacting in non-native English was associated with greater assessed English vocabulary knowledge., Conclusions: In this sample, use of non-native English did not appear to adversely affect how often, or how quickly, bilingual parents responded to their children's verbal communication bids. However, nor did we find evidence of a native-language advantage. Rather, during English-language interactions, when these bilingual parents were responsive towards their children, this was on par with rates and timing of responsiveness shown by English-speaking monolinguals. This may partly be explained by bilinguals' non-native language proficiency, and habitual use/personal dominance patterns., Implications: These data suggest no definitive drawback of non-native language use for synchronous responsiveness by bilingual parents interacting with young children with autism. However, our data also serve to highlight the complex, multifaceted nature of adult bilingualism, and indicate the need for more research - with large, well-characterised samples - to permit strong conclusions concerning how parental language-use choices may influence children's natural learning environments, including in the context of autism and developmental language impairments., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2020.)

A major topic of debate is whether children with autism spectrum disorder should be educated in inclusive or specialized settings. We examined the feasibility and preliminary effectiveness of delivering the Group-Early Start Denver Model to children with autism spectrum disorder in inclusive versus specialized classrooms. We randomly assigned 44 preschoolers with autism spectrum disorder to receive the Group-Early Start Denver Model across one school calendar year in classrooms that included only children with autism spectrum disorder or mostly children who were typically developing. Blind-rated indicators of teaching quality showed similar results across settings, which were above the local benchmark. Children showed improvements across blinded proximal measures of spontaneous vocalization, social interaction, and imitation and across distal measures of verbal cognition, adaptive behavior, and autism symptoms irrespective of intervention setting. Mothers of participants experienced a reduction in stress irrespective of child intervention setting. Across both settings, age at intervention start was negatively associated with gains in verbal cognition. Delivery of Group-Early Start Denver Model in an inclusive setting appeared to be feasible, with no significant differences in teaching quality and child improvements when the program was implemented in inclusive versus specialized classrooms.

Change over time in the age and number of children registered for autism-specific funding was examined, prior to and following introduction of the revised diagnostic criteria (the Diagnostic and Statistical Manual of Mental Disorders-fifth edition; DSM-5). De-identified data for 32,199 children aged under 7 years between 2010 and 2015 was utilised. Fluctuations were evident in the frequency and age of diagnoses, with slight increases in age of diagnosis corresponding with increases in frequency of diagnoses. The incidence of autism increased from 2010 to 2013, and then plateaued to 2015. A significant trend-relative reduction in the number of children registered to receive autism-specific funding was evident post 2013, suggesting the more stringent DSM-5 criteria may have curbed the trend of increasing diagnoses over time.

Objectives: To investigate the frequency and age at diagnosis of autism spectrum disorder (ASD) in children aged under 7 years living in Australia., Design and Participants: Analysis of de-identified data on 15 074 children aged under 7 years registered with the Helping Children with Autism Package (HCWAP; a program that provides funding for access to early intervention and support services throughout Australia) between 1 July 2010 and 30 June 2012., Main Outcome Measures: Age at diagnosis of ASD as confirmed by a paediatrician, psychiatrist and/or multidisciplinary team assessment., Results: The average age at diagnosis of ASD in children registered with the HCWAP is currently 49 months, with the most frequently reported age being 71 months. Differences were evident in age at diagnosis across states, with children in Western Australia and New South Wales being diagnosed at a younger age. Across Australia, 0.74% of the population of children aged under 7 years are currently diagnosed with ASD and registered with the HCWAP. A higher proportion of children were registered with the HCWAP in Victoria compared with other states. There was no difference in age at diagnosis between Indigenous and non-Indigenous Australians, but children from a culturally and linguistically diverse background were diagnosed 5 months earlier than other children., Conclusions: There may be a substantial gap between the age at which a reliable and accurate diagnosis of ASD is possible and the average age that children are currently diagnosed. The frequency of ASD diagnoses in Australia has increased substantially from previously published estimates.