Mediation of 6-year mid-childhood follow-up outcomes after pre-school social communication (PACT) therapy for autistic children: randomised controlled trial.

BACKGROUND: There are very few mechanistic studies of the long-term impact of psychosocial interventions in childhood. The parent-mediated Paediatric Autism Communication Therapy (PACT) RCT showed sustained effects on autistic child outcomes from pre-school to mid-childhood. We investigated the mechanism by which the PACT intervention achieved these effects. METHODS: Of 152 children randomised to receive PACT or treatment as usual between 2 and 5 years of age, 121 (79.6%) were followed 5-6 years after the endpoint at a mean age of 10.5 years. Assessors, blind to the intervention group, measured Autism Diagnostic Observation Scale Calibrated Severity Score (ADOS CSS) for child autistic behaviours and Teacher Vineland (TVABS) for adaptive behaviour in school. Hypothesised mediators were child communication initiations with caregivers in a standard play observation (Dyadic Communication Measure for Autism, DCMA). Hypothesised moderators of mediation were baseline child non-verbal age equivalent scores (AE), communication and symbolic development (CSBS) and 'insistence on sameness' (IS). Structural equation modelling was used in a repeated measures mediation design. RESULTS: Good model fits were obtained. The treatment effect on child dyadic initiation with the caregiver was sustained through the follow-up period. Increased child initiation at treatment midpoint mediated the majority (73%) of the treatment effect on follow-up ADOS CSS. A combination of partial mediation from midpoint child initiations and the direct effect of treatment also contributed to a near-significant total effect on follow-up TVABS. No moderation of this mediation was found for AE, CSBS or IS. CONCLUSIONS: Early sustained increase in an autistic child's communication initiation with their caregiver is largely responsible for the long-term effects from PACT therapy on autistic and adaptive behaviour outcomes. This supports the theoretical logic model of PACT therapy but also illuminates fundamental causal processes of social and adaptive development in autism over time: early social engagement in autism can be improved and this can have long-term generalised outcome effects.

The identification of exceptional skills in school-age autistic children: Prevalence, misconceptions and the alignment of informant perspectives.

BACKGROUND: Although autism is commonly described in terms of deficits, many autistic individuals have been found to demonstrate exceptional skills. The shift to a strengths-based approach in the field of autism necessitates increased understanding of these skills. AIMS: This study examined (1) rates of exceptional skills in autistic school-age children as reported by parents and teachers, (2) associations between exceptional skills, autism severity and intellectual disability and (3) correlations between parent and teacher reports of exceptional skills. METHOD: Parents and teachers of 76 children attending autism-specific schools in Australia completed online questionnaires. Thereafter, 35 parents and teachers who identified their child as having one or more exceptional skills were interviewed by a clinical psychologist. RESULTS: Forty parents (53%) and 16 (21%) teachers reported that their child had at least one exceptional skill (agreement between the parent and teacher reports was low; κ = .03, p = .74). In comparison, clinical psychologist assessments identified 22 children (29%) as having at least one such skill. No statistically significant relationships were identified between exceptional skills, autism severity and intellectual disability. CONCLUSION: While different exceptional skills were identified, regardless of children's intellectual functioning or autism severity, parents and teachers varied substantially in their evaluations of these skills. Furthermore, the identified prevalence rates of exceptional skills did not always align with the rates identified in previous studies. The study findings highlight the need for definitional consensus on different types of exceptional skills, and the importance of multiple criteria/multi-instrument approaches in the identification of exceptional skills in autistic children.

Sleeping Sound Autism Spectrum Disorder (ASD): a randomised controlled trial of a brief behavioural sleep intervention in primary school-aged autistic children.

BACKGROUND: Behavioural sleep problems are common in children with autism spectrum disorder (ASD); however, evidence for the efficacy of behavioural sleep interventions is limited. This study examined the efficacy of a brief behavioural sleep intervention in autistic children. It was hypothesised that the intervention would reduce overall child sleep problems (primary outcome), in addition to improvements in children's social, emotional, cognitive, academic functioning, and quality of life, and parent/caregivers' stress, quality of life, and mental health (secondary outcomes). METHODS: A randomised controlled trial was conducted with participants randomised via a computer-generated sequence to the sleeping sound intervention (n = 123) or treatment as usual (n = 122) group. Participants comprised 245 children with an ASD diagnosis. Inclusion criteria were as follows: confirmation of DSM IV or DSM-5 diagnosis of ASD, participants aged between 5 and 13 years and parent/caregiver report of moderate-severe sleep problems. Exclusion criteria were as follows: parent/caregiver intellectual disability or lacking sufficient English to complete questionnaires; and child participant with co-occurring medical conditions known to impact sleep. The intervention group received the sleeping sound intervention (2 × 50-min face-to-face sessions plus follow-up phone call) by a trained clinician. RESULTS: Change in children's sleep problems was measured by the Children's Sleep Habits Questionnaire (CSHQ) at 3 months post randomisation. Parents/caregivers of children in the intervention group reported a reduction in child sleep problems at 3 months post randomisation (effect size: E.S -0.7). There were also small effects in a number of child (internalising symptoms, emotional behavioural disturbance and quality of life) and parent/caregiver (mental health, parenting stress and quality of life) outcomes; however, these did not remain significant when controlling for multiple comparisons. CONCLUSIONS: The sleeping sound ASD intervention is an efficacious and practical way to reduce sleep problems for autistic children. This brief behavioural intervention has the potential to be embedded easily into the Australian healthcare system.

ESCAP practice guidance for autism: a summary of evidence-based recommendations for diagnosis and treatment.

Across Europe, there is increased awareness of the frequency and importance of autism spectrum disorder (ASD), which is now recognised not only as a childhood disorder but as a heterogeneous, neurodevelopmental condition that persists throughout life. Services for individuals with autism and their families vary widely, but in most European countries, provision is limited. In 2018, European Society of Child and Adolescent Psychiatry (ESCAP) identified the need for a Practice Guidance document that would help to improve knowledge and practice, especially for individuals in underserviced areas. The present document, prepared by the ASD Working Party and endorsed by the ESCAP Board on October 3, 2019, summarises current information on autism and focuses on ways of detecting, diagnosing, and treating this condition.

Anxiety characteristics in individuals with Williams syndrome.

BACKGROUND: Williams syndrome anxiety research predominantly focuses on disorder prevalence and symptomatology, categorised using standardised mental health classifications. However, the use of these assessments may not fully capture the phenotypic features of anxiety in Williams syndrome. In this study, we examined characteristics of anxiety using a formulation framework. METHOD: A semi-structured interview was conducted with thirteen parents of individuals with Williams syndrome (median age: 19, age range: 12-45, 8 females). RESULTS: Various anxiety triggers were reported, including anxiety triggered by phobias, uncertainty and negative emotions in others. The range of described behaviours was diverse with both avoidant and active coping strategies for anxiety management reported. CONCLUSIONS: Many of the characteristics described were consistent with findings in the intellectual disability and typically developing literature, although novel information was identified. The study demonstrates the utility of a formulation framework to explore anxiety characteristics in atypical populations and has outlined new avenues for research.

Parent-mediated social communication therapy for young children with autism (PACT): long-term follow-up of a randomised controlled trial.

BACKGROUND: It is not known whether early intervention can improve long-term autism symptom outcomes. We aimed to follow-up the Preschool Autism Communication Trial (PACT), to investigate whether the PACT intervention had a long-term effect on autism symptoms and continued effects on parent and child social interaction. METHODS: PACT was a randomised controlled trial of a parent-mediated social communication intervention for children aged 2-4 years with core autism. Follow-up ascertainment was done at three specialised clinical services centres in the UK (London, Manchester, and Newcastle) at a median of 5·75 years (IQR 5·42-5·92) from the original trial endpoint. The main blinded outcomes were the comparative severity score (CSS) from the Autism Diagnostic Observation Schedule (ADOS), the Dyadic Communication Assessment Measure (DCMA) of the proportion of child initiatiations when interacting with the parent, and an expressive-receptive language composite. All analyses followed the intention-to-treat principle. PACT is registered with the ISRCTN registry, number ISRCTN58133827. FINDINGS: 121 (80%) of the 152 trial participants (59 [77%] of 77 assigned to PACT intervention vs 62 [83%] of 75 assigned to treatment as usual) were traced and consented to be assessed between July, 2013, and September, 2014. Mean age at follow-up was 10·5 years (SD 0·8). Group difference in favour of the PACT intervention based on ADOS CSS of log-odds effect size (ES) was 0·64 (95% CI 0·07 to 1·20) at treatment endpoint and ES 0·70 (95% CI -0·05 to 1·47) at follow-up, giving an overall reduction in symptom severity over the course of the whole trial and follow-up period (ES 0·55, 95% CI 0·14 to 0·91, p=0·004). Group difference in DCMA child initiations at follow-up showed a Cohen's d ES of 0·29 (95% CI -0.02 to 0.57) and was significant over the course of the study (ES 0·33, 95% CI 0·11 to 0·57, p=0·004). There were no group differences in the language composite at follow-up (ES 0·15, 95% CI -0·23 to 0·53). INTERPRETATION: The results are the first to show long-term symptom reduction after a randomised controlled trial of early intervention in autism spectrum disorder. They support the clinical value of the PACT intervention and have implications for developmental theory. FUNDING: Medical Research Council.

Emotional and behavioural problems in young children with autism spectrum disorder.

AIM: To assess the frequency, pervasiveness, associated features, and persistence of emotional and behavioural problems in a community sample of young children with autism spectrum disorder (ASD). METHOD: Parents (n=277) and teachers (n=228) of 4- to 8-year-olds completed the Developmental Behaviour Checklist (DBC). Intellectual ability and autism symptomatology were also assessed. A subsample repeated the DBC. RESULTS: Three-quarters of the cohort scored above the clinical cut-off on the Developmental Behaviour Checklist Primary Carer Version (DBC-P) questionnaire; almost two-thirds of these scored above cut-off on the Developmental Behaviour Checklist Teacher Version (DBC-T) questionnaire. In 81%, problems persisted above threshold 14 months later. Higher DBC-P scores were associated with greater autism symptomatology, higher deprivation index, parental unemployment, and more children in the home but not with parental education or ethnicity, or child's age or sex. Children with IQ>70 scored higher for disruptive behaviour, depression, and anxiety symptoms; those with IQ<70 scored higher for self-absorption and hyperactivity. INTERPRETATION: The DBC identifies a range of additional behaviour problems that are common in ASD and which could be the focus for specific intervention. The results highlight the potential benefit of systematic screening for co-existing problems.

The developmental trajectory of disruptive behavior in Down syndrome, fragile X syndrome, Prader-Willi syndrome and Williams syndrome.

The aim of this study was to investigate the developmental trajectories of verbal aggression, physical aggression, and temper tantrums in four genetic syndrome groups. Participants were part of the Australian Child to Adult Development Study (ACAD), which collected information from a cohort of individuals with an intellectual disability at five time points over 18 years. Data were examined from a total of 248 people with one of the four following syndromes: Down syndrome, Fragile X syndrome, Prader-Willi syndrome, or Williams syndrome. Changes in behaviors were measured using validated items from the Developmental Behavior Checklist (DBC). The results indicate that, while verbal aggression shows no evidence of diminishing with age, physical aggression, and temper tantrums decline with age before 19 years for people with Down syndrome, Fragile X syndrome, and William syndrome; and after 19 years for people with Prader-Willi syndrome. These findings offer a somewhat more optimistic outlook for people with an intellectual disability than has previously been suggested. Research is needed to investigate the mechanisms predisposing people with PWS to persistence of temper tantrums and physical aggression into adulthood.

Cost-effectiveness analysis of a communication-focused therapy for pre-school children with autism: results from a randomised controlled trial.

BACKGROUND: Autism is associated with impairments that have life-time consequences for diagnosed individuals and a substantial impact on families. There is growing interest in early interventions for children with autism, yet despite the substantial economic burden, there is little evidence of the cost-effectiveness of such interventions with which to support resource allocation decisions. This study reports an economic evaluation of a parent-mediated, communication-focused therapy carried out within the Pre-School Autism Communication Trial (PACT). METHODS: 152 pre-school children with autism were randomly assigned to treatment as usual (TAU) or PACT + TAU. Primary outcome was severity of autism symptoms at 13-month follow-up. Economic data included health, education and social services, childcare, parental productivity losses and informal care. RESULTS: Clinically meaningful symptom improvement was evident for 53 % of PACT + TAU versus 41 % of TAU (odds ratio 1.91, p = 0.074). Service costs were significantly higher for PACT + TAU (mean difference £4,489, p < 0.001), but the difference in societal costs was smaller and non-significant (mean difference £1,385, p = 0.788) due to lower informal care rates for PACT + TAU. CONCLUSIONS: Improvements in outcome generated by PACT come at a cost. Although this cost is lower when burden on parents is included, the cost and effectiveness results presented do not support the cost-effectiveness of PACT + TAU compared to TAU alone. TRIAL REGISTRATION: Current Controlled Trials ISRCTN58133827.

Cognitive and language skills in adults with autism: a 40-year follow-up.

BACKGROUND: It is well established that very few individuals with autism spectrum disorders (ASD) and an IQ below 70 are able to live independently as adults. However, even amongst children with an IQ in the normal range, outcome is very variable. Childhood factors that predict later stability, improvement or decline in cognitive functioning remain uncertain and, in particular, very little is known about trajectories in later adulthood. METHOD: Changes in cognitive and language ability from childhood to adulthood were assessed in 60 individuals with autism, all of whom had an IQ in the average range as children. Mean age in childhood = 6 years (range 2-13 years); mean age in adulthood = 44 years (range 29-64 years). Trajectories of change and factors related to current cognitive abilities were explored. RESULTS: For the majority of participants (N = 45, 75%), who were testable both as children and adults, IQ remained very stable and language also improved over time. However, 15 individuals could not be assessed on standard tests as adults and their developmental level could be estimated only on the Vineland Adaptive Behavior Scales. Almost all these adults (apart from one who had suffered a major stroke) showed severe aggressive or self-injurious behaviours; none had ever developed language above a 3-year level, and seven had developed epilepsy. CONCLUSIONS: For most individuals with autism who had an IQ in the average range (i.e. ≥ 70) as children, childhood IQ proved a reliable predictor of cognitive functioning well into mid- to- later adulthood. However, a significant minority was no longer testable on standard tests as adults. Their current very low levels of functional ability were generally associated with severe behavioural disturbance and persisting and severe language impairment; 50% of these individuals had also developed epilepsy, pointing to the role of organic brain dysfunction. Implications for early intervention are discussed.

Development of autobiographical memory in children with autism spectrum disorders: deficits, gains, and predictors of performance.

Autobiographical memory (AM) was assessed in 63 children (aged 8-17 years) with an autism spectrum disorder (ASD) and compared with 63 typically developing children matched for age, gender, IQ, and verbal ability. A range of methodologies was employed for eliciting past experience with particular focus on the ability to recall (a) specific events, (b) the recent and remote past, and (c) semantic versus episodic memories across different lifetime periods. Results indicated that the ASD group manifested difficulties in retrieving specific memories to word cues and had poorer access to the remote past. Deficits were found in the context of intact recent memory and preserved general memory abilities, with some impairment of visual memory. Problems in retrieving episodic and semantic AMs across the life span were also evident. Qualitative analysis of memory reports suggested that the ASD group was less likely to refer to emotion in their remote memories but more likely to describe emotions in their recent memories. Important predictors of AM performance in the ASD group were central executive abilities, in particular cognitive flexibility and verbal fluency.

The Connection Between Sleep Problems and Emotional and Behavioural Difficulties in Autistic Children: A Network Analysis.

The interactions between sleep problems, autism symptoms and emotional and behavioural difficulties were explored using network analysis in 240 autistic children (mean age: 8.8 years, range 5-13 years) with moderate to severe sleep problems. Findings revealed a highly connected and interpretable network, with three separate clusters identified of the modelled variables. Depression, anxiety and behavioural difficulties were the most central variables of the network. Depression, anxiety and restricted repetitive and stereotyped patterns behaviours (RRBs) were the strongest bridging variables in the network model, transmitting activation both within and between other symptom clusters. The results highlight that depression and anxiety were highly connected symptoms within the network, suggesting support in these areas could be helpful, as well as future research.

Sleeping Sound Autism Spectrum Disorder (ASD): Cost-Effectiveness of a Brief Behavioural Sleep Intervention in Primary School-Aged Autistic Children.

Disordered sleep is common in autistic children. This study aimed to evaluate the cost-effectiveness of a brief behavioural sleep intervention, the 'Sleeping Sound intervention', in primary school-aged autistic children in Australia. A cost-effectiveness analysis was undertaken alongside a randomised controlled trial over a 6-month follow-up period from both a societal and healthcare sector perspective. Resources used by participants were collected from a resource-use questionnaire and administrative data; intervention costs were determined from study records. Mean costs and quality-adjusted life-years (QALYs) were compared between the intervention and treatment as usual (TAU) groups. Uncertainty analysis using bootstrapping and sensitivity analyses were conducted. The sample included 245 children, with 123 participants randomised to the intervention group and 122 to TAU. The mean total costs were higher for the Sleeping Sound intervention with a mean difference of A$745 (95% CI 248; 1242; p = 0.003) from a healthcare sector perspective and A$1310 (95% CI 584; 2035, p < 0.001) from a societal perspective. However, the intervention also resulted in greater QALYs compared with TAU, with a mean difference of 0.038 (95% CI 0.004; 0.072; p = 0.028). The incremental cost-effectiveness ratio was A$24,419/QALY (95% CI 23,135; 25,703) from a healthcare sector perspective and A$41,922/QALY (95% CI 39,915; 43,928) from a societal perspective; with a probability of being cost-effective of 93.8% and 74.7%, respectively. Findings remained robust in the sensitivity analyses. The Sleeping Sound intervention offers a cost-effective approach in improving sleep in primary school-aged autistic children.Trial registration The trial was registered with the International Trial Registry (ISRCTN14077107).

Generalisation of Social Communication Skills by Autistic Children During Play-Based Assessments Across Home, School and an Unfamiliar Research Setting.

We investigated autistic children's generalisation of social communication over time across three settings during a play-based assessment with different adults and explore the potential moderating effects on generalisation of age, nonverbal IQ and level of restricted and repetitive behaviours. The social communication abilities of 248 autistic children (2-11 years, 21% female, 22% single parent, 60% white) from three UK sites were assessed from 1984 video interactions in three contexts with three different interaction partners (parent/home, teaching assistant/school, researcher/clinic) at baseline, midpoint (+ 7m) and endpoint (+ 12m) within the Paediatric Autism Communication Trial-Generalised (PACT-G), a parent-mediated social communication intervention. Children's midpoint social communication at home generalised to school at midpoint and to clinic at endpoint. Generalisation was stronger from home to school and clinic than school to home and clinic. Generalisation was not moderated by age, nonverbal IQ or restricted and repetitive behaviour. Broader child development did not explain the pattern of results. The current study is the largest study to date to explore generalisation with autistic children and provides novel insight into their generalisation of social communication skills. Further research is needed to gain a more comprehensive understanding of facilitators of generalisation across settings and interaction partners in order to develop targeted strategies for interventions to enhance outcomes for young autistic children.

Using implementation science frameworks to explore barriers and facilitators for parents' use of therapeutic strategies following a parent-mediated autism intervention.

LAY ABSTRACT: Many early autism interventions teach parents therapeutic strategies to help them adjust their communication style with their children. Research has shown that this behaviour change in parents leads to improvements in child communication. It is, therefore, important to learn what factors support or hinder parents in their use of therapeutic strategies learned in such interventions. This study set out to interview parents who had participated in a research trial of the Paediatric Autism Communication Therapy-Generalised intervention. We interviewed 27 caregivers and explored their use of the strategies up to 2 years after the end of the research trial. Qualitative frameworks were used to inform interview questions and data analysis. These frameworks focused on a range of contextual factors, including parents' characteristics, their context and features of the intervention. Parents reported barriers and facilitators to using Paediatric Autism Communication Therapy-Generalised strategies across three themes: Motivating Factors; Opportunity and Support; Parent Characteristics. One of these themes, Motivating Factors, was further divided into the subthemes Compatibility and Buy-In and Alignment of Goals and Outcomes. Almost all parents reported continued use of the Paediatric Autism Communication Therapy-Generalised strategies. Facilitators included parental confidence in using the strategies and barriers included child's behaviour. Consideration of these factors can inform ways to better support parents in future autism interventions.

Characteristics of autism spectrum disorder in Cornelia de Lange syndrome.

BACKGROUND: The prevalence of autism spectrum disorder (ASD) symptomatology is comparatively high in Cornelia de Lange syndrome (CdLS). However, the profile and developmental trajectories of these ASD characteristics are potentially different to those observed in individuals with idiopathic ASD. In this study we examine the ASD profile in CdLS in comparison to a matched group of individuals with ASD. METHOD: The Autism Diagnostic Observation Schedule (ADOS) was administered to 20 individuals with CdLS (mean age = 11.34; range = 6-13 years) and 20 individuals with idiopathic ASD (mean age = 10.42; range = 8-11 years). Participants were matched according to adaptive behaviour and receptive language skills. RESULTS: Sixty-five percent (N = 13) of individuals with CdLS met the cut-off score for autism on the total ADOS score. Further analysis at domain and item level indicated that individuals with CdLS showed significantly less repetitive behaviour, (specifically sensory interests); more eye contact, more gestures and less stereotyped speech than the ASD group. The CdLS group also showed higher levels of anxiety. CONCLUSIONS: The comparison between CdLS and idiopathic ASD indicates subtle group differences in the profile of ASD symptomatology that are not accounted for by degree of intellectual disability or receptive language skills. These differences may not be evident when relying solely upon clinical and domain level scores, but may be distinguishing features of the ASD presentations in the two disorders. The findings have implications for the conceptualisation and assessment of ASD in individuals with genetic syndromes.

Ageing and autism: A longitudinal follow-up study of mental health and quality of life in autistic adults.

Background: Poor mental health is known to adversely affect functional abilities, social isolation, and quality of life (QoL). It is, therefore, crucial to consider the long-term impacts of mental health conditions as autistic adults grow older. Objectives: To explore, in a group of community-based autistic adults, the extent of: (i) autistic traits, co-occurring physical and mental health conditions; (ii) age-related differences in those conditions, and changes over time; and (iii) their impact on everyday living and QoL. Method: About Sixty-eight autistic adults (aged 19-80 years) participated in the first study (T1); 49 participants from T1 took part in a follow-up at T2 (mean retest interval 2.4 years). Standardised self-report measures of autistic traits, mental health, and QoL were completed at both time points. Results: Over two-thirds (71%) of autistic adult participants experienced at least one co-occurring condition, and over a third (37%) met the criteria for three or more co-occurring conditions. Mental and physical health difficulties were related to autistic traits and difficulties in everyday life and were consistent predictors of poor QoL at T1 and T2. Conclusion: Mental health difficulties in autism persisted into older age and did not improve over time. These findings have important implications for mental health provision for autistic adults in older age.

The importance of home: Satisfaction with accommodation, neighborhood, and life in adults with autism.

Although good quality housing and a socially cohesive neighborhood are associated with a higher well-being in the general population, housing is a rarely studied topic in autism research. In the present study, we describe the housing situation of a large sample of adults with autism and mostly (above) average intellectual abilities (n = 1429; 17 to 84 years), and examine predictors of independent living, accommodation satisfaction, neighborhood satisfaction, and satisfaction with life based on an online survey. The outcomes of independently living adults were compared with those from a Dutch community sample (n = 929). Nearly 80% of the autistic adults lived independently. Older participants, women, and those with higher self-reported IQ's were more likely to live independently. Autistic adults living independently were equally satisfied with their accommodation and neighborhood as the comparison group, but were less satisfied with their life in general. In both groups, higher satisfaction with accommodation and neighborhood was associated with higher life satisfaction. We advocate further research to better understand and anticipate the housing needs of the growing group of adults with autism. LAY SUMMARY: The living situation of autistic adults has rarely been studied. We found that 79% of autistic adults with mostly (above) average intellectual abilities lived independently. Women, older adults, and those with higher IQ's were more likely to live independently. They were equally pleased with their house and neighborhood as adults from a Dutch community sample, but autistic adults were less satisfied with their life in general.

Continuity and change in loneliness and stress during the COVID-19 pandemic: A longitudinal study of autistic and non-autistic adults.

Previous studies have suggested that autistic adults may be negatively affected by the COVID-19 pandemic and its associated restrictions. In this study, we examined continuity and change in loneliness and stress, and their predictors, in 448 autistic and 70 non-autistic adults living in the Netherlands. Autistic participants were assessed on three occasions using the de Jong Gierveld Loneliness Scale and Perceived Stress Scale (pre-lockdown (T0), first lockdown (T1), and second lockdown (T2)); non-autistic participants were assessed twice (T1 and T2). Autistic adults' loneliness and stress levels remained stable across all three time points over 8 months, but were consistently higher than those of non-autistic adults. Other predictors of higher loneliness and stress levels at the first lockdown (T1) included low perceived social support and high levels of COVID-19 related worries. Although loneliness and stress were stable at the group level, the wellbeing of some autistic adults worsened over the course of the pandemic, while others improved. For instance, adults with a mental health diagnosis (other than autism) prior to the pandemic were more likely to increase in stress over time, whereas adults with higher perceived social support were more likely to decrease in stress over time (from T1 to T2). Factors contributing to variability in outcome require further examination. Moreover, the relatively high loneliness and stress levels in autistic adults call for attention from clinicians and service providers. LAY SUMMARY: In our study, autistic adults reported feeling more lonely and stressed than non-autistic adults during the COVID-19 pandemic. People who missed support from their social network also felt more lonely and stressed. On average, people did not change substantially in their degree of loneliness or stress over time. Yet, we noted large person-to-person differences in the wellbeing of autistic adults during the pandemic.