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Background & aims: Language abilities of autistic children and children at elevated likelihood for autism (EL-siblings) are highly heterogeneous, and many of them develop language deficits. It is as of yet unclear why language abilities of autistic children and EL-siblings vary, although an interaction of multiple influential factors is likely at play. In this review, we describe research articles that identify one or multiple of such factors associated with the receptive or expressive language abilities of autistic children and EL-siblings since the introduction of the DSM-5. Our aim was to identify and summarize factors that are linked to language development in autistic children and siblings in the recent literature to ultimately gain insight into the heterogeneity of language abilities in these children. Methods: The search strategy of this review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The following databases were consulted: Embase, MEDLINE, Web of Science Core Collection, and Scopus. Inclusion criteria for studies were the presence of a sample of autistic children no older than 7 years old who were diagnosed with autism spectrum disorder per the criteria of the DSM-5. Intervention studies and studies without an explicitly reported language measure were excluded. Risk of bias assessment was completed using the Newcastle-Ottawa Scales. Ultimately, 55 articles were included in this review. Main contribution: Fifty-six factors were identified to be related to receptive or expressive language abilities of autistic children and EL-siblings. They were grouped into three main categories: biological factors; psychosocial and environmental factors; and age-related and developmental factors, each with different subcategories. Although many of the identified variables were only examined in one article, some well-researched associated factors were reported across multiple studies and were present in both autistic children and EL-siblings, in particular joint attention, nonverbal cognitive abilities and frontal EEG power. Better insight in these factors associated with language abilities in autistic children and siblings at elevated likelihood can inform future intervention strategies to reduce language deficits and its corresponding negative consequences in these children. Conclusions: Our results confirm that multiple different factors likely underlie language deficits in autism. Important aspects that should be considered are, among others, social factors such as joint attention, child characteristics such as nonverbal cognition, and neurocognitive factors.
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Background: COVID-19 restrictive measures have had a considerable impact on daily life routines, which may be especially challenging for families of children with autism. In pre-schoolers with autism, it is likely that the disruption of routines mainly impacts the presence of restrictive and repetitive behaviours (RRBs). Furthermore, influence of comorbid conditions, secondary behavioural difficulties and home environment characteristics on RRBs was explored. Method: A cross-sectional online survey design was used to collect parent-report data on 254 children with autism (2.5-6 years) during lockdown in the early months of the pandemic. RRBs were assessed using the Repetitive Behaviour Scale-Revised (RBS-R). Results: Parents reported a significant increase in stereotypic, self-injurious, compulsive and ritualistic behaviour, and restricted interests after implementation of COVID-19 restrictions. The presence of a co-occurring condition, such as language impairments or intellectual disability, was associated with more self-injurious and stereotypic behaviour. However, there was no effect of home environment on RRBs. Further, most children showed increases in internalising and/or externalising behaviour. Increased inattentive behaviour was associated with more ritualistic and stereotypic behaviour, and restricted interests. Decreases in hyperactivity were related to more restricted interests. Importantly, in a subset of children, parents reported less behavioural difficulties during the lockdown. Conclusions: Findings highlight the importance of flexible implementation and continuity of care for pre-schoolers with autism and support for parents. Further follow-up of children with autism and RRBs, and co-occurring behavioural difficulties is needed and could enhance our understanding of the long-term effects associated with sudden restrictive measures to daily routines.