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Background: Heterogeneity in adaptive behavior abilities among people with autism spectrum disorder (ASD) is expressed not only as uneven levels of impairment across domains, but also in the developmental trajectories of adaptive skills. We studied the question of whether, after accounting for global adaptive behavior development, we find evidence of heterogeneity in the trajectories of specific domains of adaptive behavior. Methods: A sample of 504 children with ASD was obtained by combining data from two independent natural history studies conducted in North America. We used a factor of curves model to explain growth between 36 and 138 months in Vineland Adaptive Behavior Scales, Second Edition (VABS) age equivalents as a function of domain‐specific and global growth processes. Results: The domain‐specific trajectories in all three domains (Communication, Daily Living Skills, and Socialization) reflected impairment relative to age expectations as well as slower‐than‐expected growth with age, and the parameters of these trajectories were moderately‐to‐strongly correlated across domains. The global adaptive behavior trajectory had an initial (36–41 months of age) developmental level of about 22 age‐equivalent months, and eventually slowed after initially increasing by about 6 months each year. The global trajectory accounted for the majority of variance in the domain‐level processes; however, additional variance remained (14%–38%) in the domain‐level intercepts, slopes, and quadratic processes. Conclusions: These results extend existing theoretical and empirical support for the hierarchical structure of adaptive behavior to include its development over time in clinical samples of children with ASD. A latent global trajectory may be sufficient to describe the growth of adaptive behavior in children with ASD; however, the remaining domain‐specific variability after accounting for global adaptive behavior development allows for the possibility that differential effects of intervention on specific domains may be possible and detectable. [ABSTRACT FROM AUTHOR]

Background: Executive functioning (EF) varies in children with autism spectrum disorder (ASD) and is associated with clinical symptoms, academic, and adaptive functioning. Here, we examined whether middle‐childhood EF mediates associations between early‐childhood autism symptoms and adolescent outcomes in children with ASD. Methods: The Pathways in ASD Cohort comprising children recruited at the time of ASD diagnosis (at 2–4 years‐of‐age) and followed prospectively across eight subsequent timepoints over ~10 years was used. A subset of Pathways participants (n = 250) with Behavior Rating Inventory of Executive Function (BRIEF)‐Parent Form data from at least one timepoint when participants were school‐aged was analyzed. A mediation framework was used to examine whether BRIEF‐measured EF across age 7–10 years (middle‐childhood) mediated associations between early‐childhood autism symptoms (measured using the parent‐report Social Responsiveness Scale across age 2–6 years) and clinical, academic, and functional outcomes, indexed at age >10–11.8 years (early‐adolescence) using the Child Behavior Checklist (CBCL)‐Internalizing and Externalizing Scales, Academic Performance from the Teacher's Report Form, and Vineland Adaptive Behavior Scales. Models were rerun substituting clinician‐rated and teacher‐rated measures, where possible. Results: Mediation models indicated a significant indirect effect of middle‐childhood EF on associations between early‐childhood autism symptoms and externalizing behavior, academic performance, or adaptive functioning in early adolescence; kappa squared (κ2) effect sizes ranged from large to small. Model findings were stable across raters. Middle‐childhood EF did not mediate associations between early‐childhood autism symptoms and adolescent internalizing behavior. Conclusions: Among children with an ASD diagnosis, middle‐childhood EF may be one pathway through which early‐childhood autism symptoms influence a variety of outcomes in early‐adolescence. An experimental study targeting middle‐childhood EF to improve adolescent academic, emotional/behavioral, and adaptive functioning is needed to evaluate the clinical meaningfulness of these findings. [ABSTRACT FROM AUTHOR]